In the FaceTime app, , scroll down and tap Block All Participants, then tap Block All Participants.
After a call has ended: Tap the call in the call history, tap Block Caller, then tap Block.
You can also swipe left on the call, tap next to the name, phone number, or email address, then tap Unblock Caller. You can also go to Settings > Apps > FaceTime, then tap Blocked Contacts. Swipe left on the contact information, then tap Unblock.
Do one of the following:
During a call: Tap Block phone numbers and contacts on your iPhone or iPadDelete a call from your call history