How to remove admin tabs for Groups single items.

bp-custom.php

<?php

function turker_remove_group_admin_tab() {
	if ( ! bp_is_group() || ! ( bp_is_current_action( 'admin' ) && bp_action_variable( 0 ) ) || is_super_admin() ) {
		return;
	}

	// Add the admin subnav slug you want to hide in the
	// following array
	$hide_tabs = array(
		'group-avatar' => 1,
		'delete-group' => 1,
	);

	$parent_nav_slug = bp_get_current_group_slug() . '_manage';

	// Remove the nav items
	foreach ( array_keys( $hide_tabs ) as $tab ) {
	  // Since 2.6, You just need to add the 'groups' parameter at the end of the bp_core_remove_subnav_item
		bp_core_remove_subnav_item( $parent_nav_slug, $tab, 'groups' );
	}

	// You may want to be sure the user can't access
	if ( ! empty( $hide_tabs[ bp_action_variable( 0 ) ] ) ) {
		bp_core_add_message( 'Sorry buddy, but this part is restricted to super admins!', 'error' );
		bp_core_redirect( bp_get_group_permalink( groups_get_current_group() ) );
	}
}
add_action( 'bp_actions', 'turker_remove_group_admin_tab', 9 );