To stop a WordPress plugin from asking to be updated you need to add the following code in your functions.php file.
It is very easy to do and shouldn't take long at all.
The main filename of a plugin is often the same as the folder name.
//Stop plugin from asking for updates
function filter_plugin_updates( $value ) {
unset( $value->response['plugin-folder/plugin-main file.php'] );
return $value;
}
add_filter( 'site_transient_update_plugins', 'filter_plugin_updates' );
This really only should be used if you REALLY don't want to the plugin to update for whatever reason.