Speaker ring adaptor modification

Hey guys, bought some of the autoleads speaker adaptors as I read through a previous post telling me that they fit perfectly, they need some modifications but I have no way of doing it! Anyone know how I can take the ring off the edge?

Shown in this thread - http://www.seatcupra.net/forums/showthread.php?t=123171

Got one done, took the p*ss!

Both done, used a hacksaw, was easy enough, just time consuming...

Cheers guys