I have found myself in a somewhat unique situation.
I have a folder. This folder, somehow, lost its owner.
In \"Advanced Security Settings for FOLDER\" under \"C
The ownership of the folder shouldn't affect its deletability, as long as the parent folder's access rights include write access for the deleting user.
A folder doesn't really lose its owner, but its owner may cease to exist. However, the folder still has an owner ID, and for most intents and purposes, that is still valid.
@birkner is on the right track. Check to see if you have any processes running in that directory, and if so, terminate them.