How do you guarantee that you removed all your private information from it?
You don't want them reading it, and you don't want the next person who rents/leases/subscribes the hardware you had reading it... I wonder how they guarantee privacy?
Who ya gonna trust?
You can’t guarantee privacy unless, as part of the lease, you get to keep the hard drive(s).
If it isn’t a solid state drive, you can use a magnet on it and you are good to go.