Recently, there have been a number of users who deface their own questions soon after posting them. In some cases, members of the community have invested time and effort in order to answer these questions, only to have all their hard work negated by the users’ acts of defacement. Hence, can moderators do anything to stop a user from defacing his/her own post? (Why would someone even consider defacing his/her post in the first place? It makes no sense to me at all.)
Flag these posts for self-vandalism and mention in the flag that the user defaced multiple posts. Moderators can and will suspend the user to stop this.
You can try to rollback the edit once, if the user vandalizes the post again, don't edit again. Don't get into an edit war, in such a case you need a moderator who has the tools to deal with this.
If needed, after a request to stop and a warning, moderators can suspend users, and they can lock questions to make them impossible to edit.