You can always use iptables to delete the rules. If you have a lot of rules, just output them using the following command.
iptables-save > myfile
vi
to edit them from the commend line. Just use the "dd" to delete the lines you no longer want.
iptables-restore < myfile and you're good to go.
REMEMBER THAT IF YOU DON'T CONFIGURE YOUR OS TO SAVE THE RULES TO A FILE AND THEN LOAD THE FILE DURING THE BOOT THAT YOUR RULES WILL BE LOST.