`-D` doesn't involve the remote at all (unless you are using something like the intentional remote:branch syntax which this example isn't). It is a force delete in that if there were commits locally in that branch and only in that branch it should still delete that branch. It should be unlikely you need that force because the first step was to branch everything as is, so it is safer to just use `-d`, but if the intention is to "blat" it from orbit anyway, `-D` is that.