how do i prune the flowering stem on a yucca plant..

I have 2 large flowering stems sticking out like towers from my yucca plant. there pretty white flowers that are now dead. how do i prune that stem? do i cut it off at the base of the plant?

What is "dead heading"?

thanks.

I just cut mine off as far down as possible. If you let it die off, in due time you will be able to pull it out.