Clearing static nat on Cisco router

I was asked to change a incoming NAT translation on a Cisco router for a customer today - however since this NAT was used to deliver all their internal email, it was never not in use, and I got the standard message below when trying to clear it:

%Static entry in use, cannot change

Thanks to, I discovered that if (in conf mode) , I prefix my (pre-prepared and ready to paste) nat changes with do clear ip nat translation, I can clear and change them fast enough to avoid the problem.