Hi Konrad,
I think to remove the Gold you may need to do it from within Play first.
I only have HS Diamond, and have one folder called "Hollywood Strings Library" which is 312 GB, so that agrees with the folder size you have. And under that are two folders, "Hollywood Strings Instruments and Hollywood Strings Samples".
When you run Play, in the Play browser page where you choose the library, do you see the two versions of "EWQL Hollywood Strings" under the Favorites tab ?.
As I said, I only have Diamond and all I see is "EWQL Hollywood Strings" ... no indication of the version, unlike the EWQLSO which definitely lists as Platinum here.
If you see the two versions inside Play, then you can highlight the Gold version and select "Remove" to delete the program references to it.
Then it should not show up again in Play.
Then I would do as Old55 says above, just rename the Gold folder and give it a quick test to make sure everything runs as expected.
You want to get that second drive mate, it will change your life :-)
Hope that helps.
Cheers - Cliff