Using Samsung's Magician software, I enabled the self encrypting capabilities of that drive ("Encrypted Drive").
Now I have reasons to undo that, but magician says
Once Encrypted Drive is enabled, it cannot be disabled directly or reverted to ‘Ready to enable status' by the user using Magician. Please contact the supplier of the subject operation system (Microsoft) or customer support for details.
Since I don't like Samsung's support so far and since I am sure Microsoft will not know, I came here, first :)
How to disable it?
I will be able to try it no sooner than Thursday.