TL;DR: Yes, you can delete chats in Beeper.

Can entire chats be deleted or removed from Beeper?

Yes, you can delete chats in Beeper. Depending on the chat network, you may be able to delete a chat just for yourself or for everyone in the conversation. 

How to delete a chat?

• You can delete a chat directly within Beeper. The option to delete for yourself or for everyone will depend on whether the underlying network supports it. 
• Alternatively, if you delete the chat on the network's native app (for example, WhatsApp or Telegram), the change should also reflect in Beeper.

What if your deletion fails?

• If you try to delete a chat and it doesn't go through, please submit a report directly from the chat in question. This helps our team look into the issue with the right context.
• If you're on Beeper Desktop, copy the error code shown and include it when submitting your report.