Disable WordPress Plugin Deactivation

Add the following code to your WordPress theme’s function.php file, or a functionality plugin.

add_filter( 'plugin_action_links', 'slt_lock_plugins', 10, 4 );
function slt_lock_plugins( $actions, $plugin_file, $plugin_data, $context ) {
	// Remove edit link for all
	if ( array_key_exists( 'edit', $actions ) )
		unset( $actions['edit'] );
	// Remove deactivate link for crucial plugins
	if ( array_key_exists( 'deactivate', $actions ) && in_array( $plugin_file, array(
		'slt-custom-fields/slt-custom-fields.php',
		'slt-file-select/slt-file-select.php',
		'slt-simple-events/slt-simple-events.php',
		'slt-widgets/slt-widgets.php'
	)))
		unset( $actions['deactivate'] );
	return $actions;
}