Fairly sure that if you delete a system (sync module), you delete all associated cameras, but for sure, if you’re adding them to a new account they will all have to be deleted, so what I did, when I did this for a test, as a belt and braces approach, I deleted all the cameras first, and then the sync module. I did not want any difficulties adding them back in with messages such as ‘already registered’, etc.
You may as well do it that way, because no way they can remain registered, and then be added to a new account, plus it’s only a small amount of extra effort to make sure your new registration runs smoothly. If they do remain registered, you would either have to recreate everything, to then delete them on the original account, or you would have to contact support. Not worth messing about, for the sake of deleting a few associated cameras, and then the sync module(s), in that order.