How do I remove an Apple ID from my new iwatch

You hubby needs to unfair Watch first, read here what he should do: Sell, give away, or protect a lost Apple Watch - Apple Support

4 Questions:

Which Watch Series?

Which watchOS is currently installed?

Which iPhone model do you have?

Which iOS is currently installed?

Check iPhone's

Settings > General > About > Software Version > ?

iOS 3.2.3 is the latest

First, your hubby needs to un-pair the Watch with his iPhone, see the link in blue in my previous post for instructions.

Then you can pair Watch with your iPhone.