Can you delete a scope from a DataStore?

I'm going to say "yes" in that you can make every key inside of that scope nil, but there isn't really a way or reason to do that.

You have a near-infinite number of scopes, and datastores for that scope, and keys for those datastores, so you should never run into any issues with having too much data to save (each key has a limit, but you can break that up by using scopes as you seem to be, and moving every 'key' up to the level of datastore.

In the case of you simply wanting to make a new set of data for some scope used in a previous version of the place, you can either make a unique identifier in the new datastores within that scope, and overwrite the data if it isn't present, or you can just use a differently named scope.