Should your relationship come to an end and you wish to transfer the page and its contents over to the artist, just roll over their image on your Artists page (yourlabel.bandcamp.com/artists) and select “remove”. If the artist doesn't already have access to their page you'll be asked to enter their email address for them to set up their account.
Removing an artist does not update any current payment settings, but artists will be able to change the payment recipient on all items on their page once they're removed.
Note that moving a release back to your label page is not possible one an artist has been removed.