Deleting folders on a backup drive

[graphicport]

Some time ago, I made a backup of my C drive. Now I need to delete the files from the Dropbox folder that was backed up on my backup drive. All files and folders deleted just fine but one. It says I don't have permission to delete it. The icon shows a large lock on it.

Can you help me figure out how to remove it? By the way, the folder was removed from my current Dropbox folder structure some time ago.

Thanks.

[Walter]

Hey @graphicport; thanks for posting on our Community!

Could you please send me a screenshot of how this looks likes on your end so that I can advise further? 

Thanks!

[graphicport]

@Walter

[Walter]

Thanks for the screenshots @graphicport!

Do you have admin privileges on the OS profile you're currently on?

[graphicport]

@WalterThanks for getting back and looking in to this. Yes, correct, I am the only user on this computer and have Administrator privileges. 

[Walter]

In that case, could you try running the disk cleanup app on your computer to see if that improves matters at all @graphicport?