How to remove all UPNP NAT rule using script?

Hello.
I reported the issues about UPNP: http://forum.mikrotik.com/t/feature-bugfix-required-upnp/105181/1
I cannot expect Mikrotik to fix them any soon, so I want to manually solve the second problem.
It seems to be difficult to delete a rule based on creation time, but at least I want to delete all rules at a certain interval.
I’ve read this: http://wiki.mikrotik.com/wiki/Manual:System/Scheduler
But I still need to know how to remove and only remove those NAT rules created by UPNP. They seems all have a “dynamic” flag, also there’s no other “dynamic” rules in my main config, so it should be safe to remove all dynamic rules, right? If yes, please anyone tell me how to do it using script, I know it’s easy in Winbox, but I need it in the Scheduler.
Thank you!

Put this in your schedule:

/ip firewall nat remove [find dynamic]

Thank you very much, It works!
But there’s another problem, even if I removed the NAT rules, those UPNP rules still shows in a UPNP client such as portmapper, and I cannot find anywhere to view/delete it by winbox or terminal, I can only view/delete them by a UPNP client. How to solve this?