Here in right side panel, right click to create a new DWORD value
with name
NoDrives (it is case sensitive), then assign number to its value
data box.

Now if
you want to hide all system drives then modify value data to 3FFFFFF.

For specific drive use values (For example, for A, B, C, D, E, F, G, H
drives,
the values are 1, 2, 4, 8, 16, 32, 64, and 128 respectively).
In this case we are trying to hide F drive, so we modify the value
data box to 32.

go into effect.
data box or delete the DWORD item.
to go into effect.