It appears you are having some difficulty with a screen anomaly on an Apple Watch. If the line remains when the Watch is asleep after rebooting it, try unpairing it from the paired iPhone and the re-pairing the two devices.
How do I remove a line from my Apple Watch?
You can remove your cellular plan at any time:On your iPhone, open the Apple Watch app.Tap the My Watch tab, then tap Cellular.Tap the information button next to your cellular plan at the top of the screen.Tap Remove [carrier] Plan. •7 Jul 2021
How do you restart Apple Watch?
Force restart your Apple Watch You should force restart your device as a last resort and only if its not responding. To force restart your Apple Watch, press and hold both the side button and Digital Crown for at least 10 seconds, then release both buttons when you see the Apple logo.
Why is Apple Watch stuck on Apple logo?
Most of the time when your Apple Watch is stuck on the Apple logo, its software crashed while turning on and your Apple Watch is frozen. Release both buttons when the Apple logo appears in the center of the Apple Watch face. Note: You may have to hold both buttons for 15-30 seconds before the Apple logo appears.
What do I do if my iPhone is stuck on the Apple logo?
1:014:39How to restart your iPhone if its frozen on the Apple logo - YouTubeYouTube