Hello shefreKS83,
Welcome to Apple Support Communities. We understand that when you received your Apple Watch back from the service center that there is an Apple ID logged in on your Apple Watch that you don’t recognize. We are happy to help.
We recommend try these steps as they may help: How to remove Activation Lock - Apple Support
"Remove Activation Lock on the device
Follow the onscreen steps to enter the Apple ID and password you used to set up your device or your device passcode. If you don't remember your Apple ID, try to sign in with an email address or phone number that you regularly use for Apple services.
Learn how to find your Apple ID or reset your Apple ID password.
Remove Activation Lock on the web if a device is offline
- Go to www.iCloud.com/find.
- Sign in with your Apple ID, email address or phone number, and enter your password.
- Select the device that you want to remove from iCloud.
- Click Remove from Account.
Start a support request
If you need help removing Activation Lock and have proof of purchase documentation, you can start an Activation Lock support request."
Please let us know if you have further questions.
Take care.