On Desktop (OS X and Windows) or on Wire for Web:
In the conversation list:
- Hover over the conversation you'd like to delete.
- Click Down Arrow ▼.
- Click Delete.
You will be asked if you want to delete the conversation and, if it is a group conversation, you can choose to leave the group.
Deleting a conversation will clear your history on all your devices, and will remove it from your active list.
For instructions on how to do this on mobile, click here.