removeChild must be called on a node

refs #10210

scripts/user-defined-actions.js

@@ -179,7 +179,7 @@ function restoreFromBackup() {
//no type check done, because we suppose the backup to be consistent
var baseNode = Property.getNode('/usr/');
if (baseNode != null)
-        Property.removeChild('events');
+        baseNode.removeChild('events');
var baseNodes = Property.getNode('/scripts/system-addon-user-defined-actions');
if (baseNodes == null) {
return;