modify user dropdown in delete page

limit-user-dropdown.php

<?php
function rkv_limit_users_delete( $query ) {

	// first fetch the screen
	$screen	= get_current_screen();
	// bail if we aren't on our user screen
	if ( ! is_object( $screen ) || empty( $screen->base ) || ! empty( $screen->base ) && $screen->base != 'users' ) {
		return $query;
	}

	// check that we are on our delete call
	if ( ! isset( $_REQUEST['action'] ) || ! empty( $_REQUEST['action'] ) && $_REQUEST['action'] != 'delete' ) {
		return $query;
	}

	// get our current user
	$user_id	= get_current_user_id();

	// call the global DB class
    	global $wpdb;

    	// modify our where clause to include the user ID
	$query->query_where .= $wpdb->prepare( " AND $wpdb->users.ID = %d ", absint( $user_id ) );

	// send it back
	return $query;

}

add_filter( 'pre_user_query', 'rkv_limit_users_delete' );