Hi
If your Apple Watch is unpaired according to your iPhone, but not according to your Apple Watch and if you also cannot interact with your Apple Watch due to a damaged screen, then follow these steps to unpair and erase it:
- On a computer, using a web browser, go to iCloud.com and sign in with your Apple ID and password.
- Go to Find My iPhone.
- Select All Devices, then click on your Apple Watch.
- Click Erase Apple Watch > select Next until the watch is erased.
- Click X next to your Apple Watch.
More information: