How to turn off screen mirroring on iPhone X?

Please help. I accidentally turned on screen mirroring and now it says "looking for Apple TV." And it just won't go away. I've tried restarting my phone, turning on airplane mode and turning off Bluetooth. I don't even have an Apple TV and never did. What can I do to turn it off.

IPhone 6 not getting and signal or data?

So my antenna was broken so I replaced the cellular antenna, I replaced the Wi-Fi antenna, I cleaned it all and it still just says searching, I don't know what else I can do it's really stressing me out

Why does my iphone 5s not work properly?

Why does my iphone 5s not work properly?

Added (1). Can anyone help me with my i-phone 5s problem? Every time I phone my friend he can't hear me but I can hear him. I then have to hang up and immediately phone him back and then he can hear me! This only happens with his number and no one else. I can call him on other peoples mobile phones and using a landline with no problem.