My other phone that the Apple Watch was connected got destroyed and I can’t un pair it

See this Apple support link→Unpair and erase your Apple Watch - Apple Support

About halfway down the page, see the section: How to erase your Apple Watch if you don't have your iPhone

You need to reset the watch: tap Settings > General > Reset > Erase All Content and Settings.

Scroll down on this page to see the details:

https://support.apple.com/en-gb/HT204568

if you're trying to pair it with a different iPhone, this will walk you thru it

How to pair your Apple Watch with a new iPhone - Apple Support