How do I change the number that’s set up with my iCloud

If you’re asking about the telephone number with your iCloud account, you’d want to update the telephone number that is on your Apple ID. On iOS, go to Settings > Your name > Name, Phone Numbers, Email. You can edit the telephone numbers that are associated with your Apple ID on that screen. If you aren’t able to remove the number from that screen, make sure you have it turned off for FaceTime and iMessage under settings first.