It is best to simply unpublish them till you decide where to move your hubs to. Matt Myer told me that when a hub is unpublished it can be published on another site without being flagged on HP or the new site as duplicate copy.
So, it is best to unpublish the hubs, decide where you want to move them, publish on the new site, then come back to HP and delete the hubs you moved. This is how I do it and I have had no problems.
If you remove your hubs and they just sit in a file on your computer, it is difficult to prove copyright claim if someone steals your hubs.
Verify this with Christy Kirwan (what Matt told me), but like I said, it works for me.