if you dont want it on there any more my advise would be take to a bike shop where people like me have the tools to remove it with ease and with out damaging the hub ht e most they should charge is 50p or if there friendly they wil do it for free
spray it and let it soak in plus gas for 1 day that should make it easier if not local bike shop you can not resist the powers of the shop lol if you live lowestoft il get it off for ya
If so, you did the right thing: keep the cassette in place with one tool, while trying to unlock the smallest cog counterclockwise with the other. Just to make sure: could you post a close-up of the hub taken from the side with the smallest cog?
It is not like that one on page 9. That one is a 8s, mine 7s (it comes from a '92 S-works M2). Probably that does it make look different. Mine looks more like that Superbee cassette (the one in front)