Hello Kaila,
I'm Shalom and I'd happily help you with your question. In this forum, we are Microsoft consumers just like yourself.
To delete a chat history in Microsoft Teams, you can follow these steps:
Open the Microsoft Teams app and select the conversation you want to delete. Click the three dots icon at the top right corner of the conversation window.
Select “Delete Conversation” from the drop-down menu. Please note that once you’ve selected Delete, the chat will be permanently removed from your chat list and conversation history will be deleted. However, the chat will remain for the other person. If you delete a one-on-one chat, the other person won’t know that you’ve deleted it.
If you’re using Microsoft Teams’ mobile app, long press the message you wish to delete. You will be presented with a menu. Confirm you wish to delete the message. This will delete the chat from the Teams mobile app and replicate the change on your desktop app.
I hope this helps! Let me know if you have any other questions.
Best Regards, Shalom