Hi Timothy_58,
Thanks for your post. Based on your description, you want to delete a “sending” chat message in Teams. Please help to confirm you have permission to delete it, you can check it via
Office 365 Admin center: go to Office 365 Admin center->settings->services & add-ins->Microsoft Teams->Messaging.
Note: you can check it if you have admin permission. If no, please ask your admin to check it.
After making sure you have permission to delete it, then you can choose the message and click More options like below:
If I have any misunderstanding or this issue is different scenario, please feel free correct me, and you can provide a screenshot about this “sending ” message to us.
Regards,
Richard