Time Machine - can't empty trash. "folders" is in use

I tried the search function, can't find anything "new" about this issue.

I have an external RAID drive that I decided to let time machine use. It had backed up some very large data that I had forgotten to remove from my iMac. I deleted the files in question and wanted to delete the backups and start over. Unlike most things Mac, time machine is not very intuitive. Not only that, there are a million backups and the only way I can get through them is by this little up and down arrow, and you can't even hold it down. I read to do it manually, so I selected a ton of backups and trashed them. It put them from the RAID to my trash. When I try to delete the trash I get the following error:

"The operation can't be completed because the item "folders" is in use." There is no folder called "folders" in the trash.

All the folders are empty in the trash, but there are a lot of folders. I have tried every single hack I can find including terminal commands, NOTHING will empty these folders out of my trash. I read that because there is a folder called "Macintosh HD" that it wouldn't delete it. I renamed it and it still won't delete. I'm at my wits end, can someone help? I have a lot more time machine backups that need to be deleted still, and I need a fast method for those as well, preferably not within the time machine app since it's so cumbersome to use.