Upgraded my Apple Watch 5 to ultra

Hi BettsyBlade

Welcome to the Apple Community.

Congratulations on the new Watch Ultra.

Wondering if you want to keep both watches, they can both be paired to the iPhone:

Apple Support's article: Set up and pair your Apple Watch Ultra with iPhone – Apple Support

also gives all the info.on switching been Watches.

(Only one Apple Watch can be active at a time... more info in the article linked below.)

Use more than one Apple Watch with your iPhone - Apple Support

Re: Don’t want lose any of my data or stuff ?

The Watch data is generally back up to iPhone.

also: Unpairing a Watch backs up its data to iPhone.

The back-up data can then be restored if required,

If you want to erase the old Watch:

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

There's a useful user guide online:

Apple Watch Ultra User Guide – Apple Support

All the best :-)