Q: getting new iphone and number. how do i discontinue icloud on current phone and set up new phone

If you're doing this in preparation for giving away or selling the old device, follow these steps

What to do before selling or giving away your iPhone, iPad, or iPod touch - Apple Support

If you plan on keeping both devices, you don't have to do anything to the old one in terms of Apple ID. Just make sure you make a fresh (encrypted) backup to iTunes, so you can later Restore it onto the new iPhone.

A single Apple ID supports multiple devices. Just go thru the set up instructions that you'll see on the new phone and restore the backup noted above.