VFR Tower?

Class D towers controlled by Centers are extremely common.
I controlled two as a Center controller. Procedure was pretty much the same as it was for the one at the approach control I was at. I think some have agreements (and/or automation) for releases that don’t require calling up the controlling radar facility, but ours were all done by landline. And, of course, they’d have to call to give up control, like you already said.