Turn Off Auto Update for Single Plugin

you place this in your theme’s functions.php

// Disable update notification for individual plugins - see my example of plugin block-spam-by-math-reloaded as to how to use this function

function filter_plugin_updates( $value ) {
    unset( $value->response['plugin-folder-name/plugin-file-name.php'] );    
    return $value;
}

add_filter( 'site_transient_update_plugins', 'filter_plugin_updates' );