Deleting a message is easy.
On iOS/Apple devices:To delete a message thread, swipe it left and press DeleteTo delete a specific message inside a thread, tap and hold the message you want to delete and press Delete
On Android devices:To delete a message thread or a specific message, tap and hold the thread or message and press Delete
You cannot remove system messages.
You can only remove messages visible to you. Your Circle Members will still be able to see the messages you deleted on their device.