Clear all revision in you single site or multisite with WP-CLI Command. You can also keep few of them with the help of this command.

mu-delete-revision.php

<?php
/**
 * Plugin Name: Clear Old Revisions
 * Plugin URI: http://buddydevelopers.com
 * Description: plugin to clear old revision data.
 */
/**
 * Class to clear old revision data.
 */
if (  defined( 'WP_CLI' ) && WP_CLI ) {
	class Clear_Revision_Command extends WP_CLI_Command {
		/**
		 * Delete old revisions
		 *
		 * ## OPTIONS
		 *
		 * [<keep>]
		 * : Number of revisions to keep per post. Defaults to WP_POST_REVISIONS if it is an integer
		 *
		 * [--post_type=<post-type>]
		 * : Clean revisions for given post type(s). Default: any
		 *
		 * [--after-date=<yyyy-mm-dd>]
		 * : Clean revisions published on or after this date. Default: none.
		 *
		 * [--before-date=<yyyy-mm-dd>]
		 * : Clean revisions published on or before this date. Default: none.
		 *
		 * [--post_id=<post-id>]
		 * : Clean revisions for given post.
		 *
		 * [--hard]
		 * : Hard delete. Slower, uses wp_delete_post_revision().
		 *
		 * [--dry-run]
		 * : Dry run, just a test, no actual cleaning done.
		 *
		 * ## EXAMPLES
		 *
		 *     wp revisions clean
		 *     wp revisions clean 5
		 *     wp revisions clean --post_id=2
		 *     wp revisions clean 5 --post_type=post,page
		 *     wp revisions clean --after-date=2015-11-01 --before-date=2015-12-30
		 *     wp revisions clean --after-date=2015-11-01 --before-date=2015-12-30 --dry-run
		 */
		public function clean( $args = array(), $assoc_args = array() ) {
			global $wpdb;
			if ( ! empty( $assoc_args['post_id'] ) ) {
				$posts = array( $assoc_args['post_id'] );
			} else {
				if ( empty( $assoc_args['post_type'] ) ) {
					$post_types = $this->supports_revisions();
				} else {
					$post_types = explode( ',', $assoc_args['post_type'] );
				}
				$where = '';
				$post_type_where = array();
				foreach ( $post_types as $post_type ) {
					$post_type_where[] = $wpdb->prepare( 'post_type = %s', $post_type );
				}
				$where = ' AND (' . implode( ' OR ', $post_type_where ) . ')';
				if ( isset( $assoc_args['after-date'] ) && isset( $assoc_args['before-date'] ) ) {
					$where .= $wpdb->prepare( ' AND (post_date < %s AND post_date > %s)', $assoc_args['before-date'], $assoc_args['after-date'] );
				} else if ( isset( $assoc_args['after-date'] ) ) {
					$where .= $wpdb->prepare( ' AND post_date > %s', $assoc_args['after-date'] );
				} else if ( isset( $assoc_args['before-date'] ) ) {
					$where .= $wpdb->prepare( ' AND post_date < %s', $assoc_args['before-date'] );
				}
				// get all IDs for posts in given post type(s).
				$posts = $wpdb->get_col( "SELECT ID FROM $wpdb->posts WHERE 1=1 {$where}" );
			}
			$total = count( $posts );
			$notify = \WP_CLI\Utils\make_progress_bar( sprintf( 'Cleaning revisions for %d post(s)', $total ), $total );
			if ( isset( $args[0] ) ) {
				$keep = intval( $args[0] );
			} else if ( true === WP_POST_REVISIONS ) {
				WP_CLI::error( 'WP_POST_REVISIONS is set to true (keeps all revisions). Please pass a number.' );
			} else {
				$keep = WP_POST_REVISIONS;
			}
			$total_deleted = 0;
			foreach ( $posts as $post_id ) {
				$revisions = get_children( array(
					'order'                  => 'DESC',
					'orderby'                => 'date ID',
					'post_parent'            => $post_id,
					'post_type'              => 'revision',
					'post_status'            => 'inherit',
					// trust me on these.
					'update_post_meta_cache' => false,
					'update_post_term_cache' => false,
					'fields'                 => 'ids',
				) );
				if ( ! $revisions ) {
					$notify->tick();
					continue;
				}
				$count = count( $revisions );
				if ( $count > $keep ) {
					if ( $keep > 0 ) {
						$revisions = array_slice( $revisions, $keep, null, true );
					}
					$total_deleted += count( $revisions );
					if ( isset( $assoc_args['hard'] ) ) {
						foreach ( $revisions as $id ) {
							if ( empty( $assoc_args['dry-run'] ) ) {
								wp_delete_post_revision( $id );
							}
						}
					} else {
						$delete_ids = implode( ',', $revisions );
						if ( empty( $assoc_args['dry-run'] ) ) {
							$wpdb->query( "DELETE FROM $wpdb->posts WHERE ID IN ($delete_ids)" );
						}
					}
				}
				$wpdb->flush();
				$notify->tick();
			}
			$notify->finish();
			if ( ! empty( $assoc_args['dry-run'] ) ) {
				WP_CLI::success( sprintf( 'Dry Run: Will remove %d old revisions.', $total_deleted ) );
			} else {
				WP_CLI::success( sprintf( 'Finished removing %d old revisions.', $total_deleted ) );
			}
		}
		/**
		 * List all revisions
		 *
		 * ## OPTIONS
		 *
		 * [--post_type=<post-type>]
		 * : List revisions for given post type(s).
		 *
		 * [--post_id=<post-id>]
		 * : List revisions for given post. Trumps --post_type.
		 * 
		 * [--yes]
		 * : Answer yes to the confirmation message.
		 *
		 * ## EXAMPLES
		 *
		 *     wp revisions list
		 *     wp revisions list --post_id=2
		 *     wp revisions list --post_type=post,page
		 *
		 * @subcommand list
		 */
		public function list_( $args = array(), $assoc_args = array() ) {
			global $wpdb;
			if ( ! empty( $assoc_args['post_id'] ) ) {
				$revs = $wpdb->get_results( $wpdb->prepare( "SELECT ID, post_title, post_parent FROM $wpdb->posts WHERE post_parent = %d", $assoc_args['post_id'] ) );
			} else if ( ! empty( $assoc_args['post_type'] ) ) {
				$post_types = explode( ',', $assoc_args['post_type'] );
				$where = '';
				foreach ( $post_types as $post_type ) {
					$where .= $wpdb->prepare( ' OR post_type = %s', $post_type );
				}
				// get all IDs for posts in given post type(s).
				$ids = $wpdb->get_col( "SELECT ID FROM $wpdb->posts WHERE 1=2 {$where}" );
				$post__in = implode( ',', $ids );
				// get revisions of those IDs.
				$revs = $wpdb->get_results( "SELECT ID, post_title, post_parent FROM $wpdb->posts WHERE post_type = 'revision' AND post_parent IN ({$post__in}) ORDER BY post_parent DESC" );
			} else {
				$revs = $wpdb->get_results( "SELECT ID, post_title, post_parent FROM $wpdb->posts WHERE post_type = 'revision' ORDER BY post_parent DESC" );
			}
			$total = count( $revs );
			if ( $total > 100 ) {
				WP_CLI::confirm( sprintf( 'List all %d revisions?', $total ), $assoc_args );
			}
			$formatter = new \WP_CLI\Formatter( $assoc_args, array( 'ID', 'post_parent', 'post_title' ), 'revisions' );
			$formatter->display_items( $revs );
			WP_CLI::success( sprintf( '%d revisions.', $total ) );
		}
		/**
		 * Supports Revisions
		 *
		 * Get list of post types that support revisions
		 *
		 * @return array
		 */
		private function supports_revisions() {
			$supports_revisions = array();
			foreach ( get_post_types() as $post_type ) {
				if ( post_type_supports( $post_type, 'revisions' ) ) {
					$supports_revisions[] = $post_type;
				}
			}
			return $supports_revisions;
		}
	}
	WP_CLI::add_command( 'revisions', 'Clear_Revision_Command' );
}