How do I unlink my Apple Watch from someone else's account?

Did your Apple Watch had a previous owner, or did you buy it new?

Did you follow the steps mentioned in this article to set up the watch, especially the part #5 about the Apple ID?

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If asked, enter your Apple ID password. If you aren’t asked, you can sign in later from the Apple Watch app: Tap General > Apple ID, then sign in. Certain features that require a cellular phone number won’t work on cellular models of Apple Watch unless you sign in to iCloud.

If Find My isn't set up on your iPhone, you'll be asked to turn on Activation Lock. If an Activation Lock screen appears, your Apple Watch is already linked to an Apple ID. You need to enter the email address and password for that Apple ID to continue set up. If your Apple Watch was previously owned, you might need to contact the previous owner to remove Activation Lock.

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copied from: Set up your Apple Watch - Apple Support

If your iPhone is being used with the wrong Apple ID mail address, in Settings/Your Name/Apple ID, and shows your husbands mail address, scroll down to the end of the screen and tap on Log Out.

Then log in again with your Apple ID credentials.

After that you should be able to set up your Apple Watch with your Apple ID shown.

But, if your iPhone has been used with his Apple ID to download apps and other content, don't delete it from the Apple ID settings page.

You can manage your Apple ID settings as described here:

About your Apple ID email addresses - Apple Support

Manage and use your Apple ID - Apple Support

Did you make sure, that his mail address is not listed as one of your Apple Account mail addresses?

About your Apple Account email addresses - Apple Support

you should have your husband take all the following steps

What to do before you sell, give away, or trade in your Apple Watch, or buy one from someone else - Apple Support

then you should be able to set it up without any traces of his account being present on the watch