I'm just guessing here, but I would be surprised if the magnet on the 10" is screwed onto the basket. Besides commercial drivers that often require in field repair and very high end home woofers, the magnets are usually glued on with a high grade adhesive. I’ve removed magnets from woofers in the past by brute force, but that can be problematic.
As long as there is no signal applied to the woofer, I’m pretty sure it will act as a passive radiator. I would suggest posting this on the Parts Express forum where I’m sure you’ll get some very good advice.