Can someone stop receiving location from a friend who has shared their location?

If you don't want to share your location, you can open Find, tap People at the bottom - find the person you don't want to share your location with, tap in and select "Stop Sharing My Location" or just "Remove Person's Name"

You cannot block requests from people, but you can choose to ignore them.

Alternatively, you can try blocking the person completely, however this will also prevent receiving calls, messages, FaceTime, etc.

You can see how to block contacts here:

Block phone numbers, contacts, and emails on your iPhone or iPad - Apple Support