Look for the editing pages, and replace them with new ones. That would be the first thing. If it still does it, then look a little further afield.
You can update your Moodle but using the csv optional downloads or build another Moodle, clean and unchanged, then change any or all pages by FTP
. Personally, I use the clean copy, simple and easy, maintains versions as well. The connectionless process of http allows for this kind of hocus pocus. All you need do is to delete a page and upload
a clean version of it. Do not try to overwrite, even with FTP. Delete is safer and do it quickly. Minimum of fuss and if there is no-one online at that moment, no-one ever knows.