Delete a folder that lost its owner

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 "Current owner:" is displayed:

Unable to display current owner.

I am trying to delete this folder with no success. I have tried taking ownership with both my user and the Administrator user and both yield

Unable to set new owner on FOLDER, Access is denied

I have tried to grant administrator full privileges via the Windows shell running as administrator:

icacls FOLDER /grant administrators:F

And I have tried to remove the folder via the Windows shell running as administrator:

rmdir FOLDER /s

which return:

Access is denied

Does anyone have any idea as to how I can delete this folder?