I’ve had my Apple Watch for years but I’ve changed phones and now I don’t know my old email to disconnect it from that one

Tiana838 wrote:

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Did you also change Apple IDs, when you changed iPhones? If not, then you’re using the same Apple ID.

To unpair from an iPhone you no longer have, but the same Apple ID, scroll down here: Unpair and erase your Apple Watch - Apple Support

If you did switch Apple IDs too (unfortunately that’s generally a bad idea), then you will need to regain access to that Apple ID (as mentioned above), or scrounge up the original purchase receipts for the Apple Watch and ask Apple to remove Activation Lock.

You'll need to look it up because you can still unpair it if you know the Apple ID by going to iCloud.com/find and log in with that Apple ID and password, click on "show all devices", click on the device, then click remove.

To figure out your Apple ID use this article: If you forgot your Apple ID email address or phone number - Apple Support