Please keep in mind that you can't completely delete a chat with a user, but you can hide it so it doesn't clutter your conversation list.
Desktop version:
To hide a chat:
- Go to the "Chats" section in the "My activity" area.
- Find the user whose chat you want to hide from the list on the left.
- Hover your mouse over the user's name, click on the three dots, and select "Hide chat" from the menu. You can also find this option by clicking on the "More" button.
Mobile version:
To hide a chat:
- Open the chat with the user.
- Tap the three dots in the top-right corner of the screen.
- Click the "Hide chat" button and confirm your action.