He has an oral lease by virtue of his possession, but he is destroying your property. You can evict him due to the ongoing destruction. Provide him with a 3 day notice, take lots of photos of the destruction and don't accept any more rent. He may move by the end of the month, and if he doesn't file a forcible entry and detainer in eviction court. They should have forms and instructions at the filing desk and possibly online.
Actively practicing law in Texas. Inactive licenses in Arizona and Georgia. All answers are general in nature and no attorney/client relationship exists in this forum.
Attorney Smith has given you great advice. I suggest you follow it to prevent any further damages/delay.
Rengin Bekhtyar's answer to a legal question on Avvo does not establish an attorney-client relationship.