Call won't leave my MacBook Air screen
"On my Mac I was calling someone but ever since, the call would not leave my screen.
[Notification Center] If anyone knows how to end it it would be a help"
[Re-Titled by Moderator]
MacBook Air 13″
If you have a Mac and an iPhone connected to the same wireless LAN, you can receive phone calls on the Mac, and you can place phone calls on the Mac using FaceTime. This has been in macOS since at least High Sierra. Perhaps the OP has an iPhone and is taking advantage of this feature?
Make and receive phone calls on Mac or iPad - Apple Support
Make and receive phone calls in FaceTime on Mac - Apple Support
Another possibility is that the OP is making FaceTime calls over the Internet to another Mac (or Apple device).
Use FaceTime on Mac - Apple Support
