ifconfig -- how to remove address and mask?

[freebsd at dreamchaser.org]

running 6.1,

Is there a way to bring an interface down and remove the ipaddr and mask?
I've tried ifconfig destroy with no effect, and I'm getting tired of
twiddling rc.conf and rebooting...

The problem arises when testing a new configuration where an existing
interface has an assigned ip addr, and is then changed to be used with
pppoe.  The routine tables get really confused...

Thanks,

Gary