Accept a video or audio call and end a current call: Click End & Accept.
Accept an audio call and put the current audio call on hold: Click Hold & Accept. When you end the new call, the call on hold resumes. You can pause one audio call at a time.
You can also accept a Group FaceTime call from Messages. When invited, just click Join in the FaceTime message bubble.
When you’re on a call, you can do any of the following.
Delete the call history in FaceTime on MacApple Support article: If FaceTime isn’t working on your Mac