Removing folders created by Microsoft's OneDrive

I used Microsoft's OneDrive for a very short time during which it wiped out my data allowance in just 5 days. I have since removed the application from all of my Apple devices, but I cannot delete the folders it created - says I don't have permission. Any idea how I can remove the folders? I can remove their contents, but as there are over 50,000 files, this will take a long time!