Side sill removal

[1.8t]

So I am probably retarded, but how in the hell do I release the side sill from the rear 1/4 panel where they meet right above the exhaust outlet? Putting in my ARH headers and I can't see any hardware, but it will not release from this joint.

Do I have to remove the rear tire and wheel liner to get at bolts behind this joint?

Any help is appreciated.

Thanks