macOS Applescript -hiding desktop drive icons

I've had success with a couple of Applescript scripts in hiding hard drive icons on the Finder desktop that I don't need to access (the Mac Pro uses them for backup and cache purposes):

Hiding the drive icon

Making the drive visible again

However I'm not able to hide a certain drive (nothing happens when I run the "hide" script). This is a bootable backup drive which is daily updated using Chronosync. Is it un-hideable because it's bootable? Is there anything else I can do to hide this drive icon from the desktop?
I'm using OSX 10.6.8.

Yes, but this hides ALL drives, or ALL external drives, which is not what I want.

Thanks. I tried the Terminal suggestion there and the result was the same as with my Applescript, but.... unlike Applescript it gave me an error message: "Permission denied".
So I tried adding myself as a new user for the drive, enabling read/write" and then it worked.

Thanks for heading me in the right direction. I'll have to figure out the correct ownership for my drives.