How to wipe entire iCloud library without having to download it first? I have a Macbook and an iPhone who are both not syncing to iCloud, but the iCloud itself is filled with pictures that i want deleted. Is there any way of doing this without first having to delete thousands of pictures on one of them? 

I tried doing it on the iPhone but apparently it says you can cancel it for 30 days, meaning i still cannot use the iCloud library since they're still in my "recently deleted", meaning if i enable it on any device, it's still going to download those thousands of pictures. Is there a way to just hard delete everything?
You can delete them on iCloud.com but deleting thousands will be painful. Photos can be permanently deleted immediately by deleting them from the "Recently Deleted" album.

Just enable iCloud Photo Library on the Mac using the "Optimized Size" setting and placeholder/thumbnails for the photos will quickly appear. Delete them from the regular Photos view then delete them again from "Recently Deleted" and you should be good.