The xowiki data model is really the OpenACS content repository. It is the same datamodel as e.g. in file-store, just with a few attributes more. The content repository has a delete function, which does what the name indicates. This topic pops up from time to time, but is not resolved.
Even a dialog "delete really" does not help from my experience, because people get used to it an press enter without thinking. The trash can metaphor would be the best solution in my opinion, but is not implemented.