Remove admin bar & keep end users out of the WordPress backend

remove-admin-bar.php

/**
 * Remove admin bar & admin access for non-managers & non-admins
 * @access  public
 * @since   0.1.0
 */
add_action('admin_init', 'no_mo_dashboard');
add_action('after_setup_theme', 'remove_admin_bar');
function no_mo_dashboard() {
	if ( ! current_user_can( 'edit_others_posts' ) && '/wp-admin/admin-ajax.php' != $_SERVER['PHP_SELF'] ) {
		wp_redirect( site_url() ); exit;
	}
}

function remove_admin_bar() {
	if (!current_user_can('administrator') && !is_admin()) {
		show_admin_bar(false);
	}
}