Once you publish a Release you cannot delete it. Think of publishing on Nina as being similar to releasing a vinyl record. Once someone has collected it you can’t recall it from their house.
Soon you will be able to make edits to a Release by making a new version of the Release. You can not edit the price or edition size of a Release. Anyone who has purchased your Release will be able to see any versions of your Release that were available after the time they collected it.