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.

Follow the instructions here

Look for the AirPlay icon and click it to change settings. It's the rectangle with a triangle at the bottom.

"How to AirPlay video and mirror your device's screen"