Factory Resetting HDD

So long story short, I added another 3TB drive to my system for a backup and accidentally formatted it as MBR, and I can't change it back as even with all partitions removed.
It shows up naturally in MBR as 500MB for the system (can't remove), 2.1TB (The max for the format) and the remainder. The last two are formatted, but the option is still greyed out.
I believe the 'system reserved' 500MB partition is preventing this, so I'm thinking just a straight factory reset will allow me to reconfigure it.
Thoughts?
 


Yes you can check by disconnecting your main drive, if it boots than youve got a problem
 


needed to be done anyways, you moved your boot to a new hdd and formatted and locked it up in a very secure way.

you fixed it, move on .