The disk "External HD" couldn't be ejected because the Finder is Using It Question?

I have downloaded some music sample packs and have deleted all the components I need.

When I open the sample pack there is a remaining folder inside, it is named "__MACOSX". Nothing is in this folder and it is complete garbage. The only issue I have is that I can not delete/empty my trash can with it inside. It gives me this error message (below).

The operation can’t be completed because the item “______” is in use.

Is there anyway to fully delete these folders? I know in the past they had "secure empty trash" put they did away with it. I just want to delete these folders so I can properly eject my external HD.

When I try to eject my external HD it gives me this error message now (below).

"The disk "External HD" couldn't be ejected because the Finder is Using It. Stop the Finder action and then try to eject the disk again."

I just power down my MacBook now every time to eject it somewhat safer. Any solutions would be greatly appreciated. Thank you!

Not sure how "Nothing" could be complete garbage, but other than that I usually find that restarting the mac fixes these errors. Maybe there is a program that runs on startup which may be worth trying to isolate.