How to delete all Drupal content owned by a particular user?
A possible alternative to achieve what you're trying to do, is to use a combination of modules Views and Views Bulk Operations (VBO). With these modules in place, you could simply create a view of all the nodes "owned" by a user, and simply use the out-of-the-box VBO action to "delete an item" (after adding a VBO field like "Bulk operations: Content"). And by creating a similar VBO view, using the VBO field "Bulk operations: Content revision", you can probably also cleanup up the revision data.

If you need more sophisticated business logic to decide about the criteria related to "owned by a user", you could add Rules to such solution also and implement a variation of the solution described in my answer to "How to bulk update select list fields?", i.e.:


Create a Rules Component with a Rules Condition to checks if the node matches the criteria you're interested in.
Create a VBO enabled view of all nodes to be checked, whereas you'll use the Rules Component as your custom VBO action.


Done ...