There are already a number of tutorials for the rear clam removal, but for most the pictures are either gone or a bit cryptic.
I had to remove mine to check the state of things before contemplating doing my subframe shims. I took the opportunity to make a photo guide of what is the default method to get the rear clam off... of course there are variants (like not removing the headrests etc etc...
Hence this is the long way around, but at least it is the "safe" way.
1) Start by removing the seats. If the dreaded passenger screw has already been removed and lost (like on mine) it is a fairly simple thing to do. Use the long extensions added together to get to the passenger rear allen screws without much hassle, and disconnect the safety belt from the seats before extracting them of the tub (17mm socket). It is also a good opportunity to clean the bottom of the tub.
2) Next up are the headrests. You will need to remove them to be able to tilt the roll bar cover forward. Start by gently wiggling the hard plastic cover behind the headrests towards the back window. They are sort of velcroed in place. You can also start removing the plastic rivet screws that hold the central liner in place.