You can't delete specific messages on Smitten. Nonetheless, you can erase entire conversations by unmatching a user. Unmatching will result in both you and the other person being removed from each other's match lists.
To unmatch someone:
- Open your chat with that person
- Tap on the 3 dots in the upper right corner
- Choose Unmatch
It's important to note that unmatching is a permanent action and cannot be reversed.