Board Thread:Support Requests - Getting Started/@comment-26108271-20150314053818/@comment-452-20150314130527

It is possible.

An admin can export the page with full history, edit the XML file and replace the IP with a user name, delete the page, then re-import the edited history. (It would probably be better to only delete and import the one revision, but that takes a few more steps.)

Of course, this requires the admin to want to do this, and it would be too much trouble for most.