This hook allows you to remove items from the bulk actions dropdown on any specified admin screen.
Bulk actions are a simple associative array.
The filter hook follows the format 'bulk_actions-screenid', where screenid is the id of the admin screen that you want to affect.
add_filter('bulk_actions-screenid','function_name');
The following example removes an action from the Bulk Actions drop-down on the Users page:
<?php
function my_custom_bulk_actions($actions){
unset( $actions['delete'] );
return $actions;
}
add_filter('bulk_actions-users','my_custom_bulk_actions');
?>
Pay attention to the actual option values, not just the text displayed in the dropdown, on the page you wish to modify. For example, the delete option on the Plugins list page is "delete-selected" (as of 4.2.2).
As of version 4.7, custom bulk actions can be added using this filter. You can add functionality to custom bulk actions using 'handle_bulk_actions-screenid', where screenid is the id of the admin screen that you want to affect. See http://core.trac.wordpress.org/ticket/16031
Administration Screen Id Reference
A workaround for Adding a Custom Bulk Action
Details to adding custom bulk actions