Hide Drive using CMD
1] Open an elevated command prompt, type Diskpart and hit Enter.
2] Type List Volume and hit Enter.
3] Now type select and the numeral against the letter of the Drive (eg. it could be G Drive), which you want to hide. For instance, it could be Select Volume 6. Hit Enter.
4] Finally, type Remove Letter G and hit Enter.
You will see a message – Diskpart successfully removed the drive letter or mount point.
To show the hidden drive, follow steps 1, 2, 3 mentioned above.
Now type Assign Letter D and hit Enter. This will show the drive in Explorer.
If you need a detailed walk-through, see our forum post titled Hide or show your hard drive partitions using Diskpart.
These are the 4 ways you can hide a drive natively, in Windows.
UPDATE: You can also use freeware HideCalc to hide disk drive in Windows.