Reverting to a "before developer" version

[Troy Hall]

I branched our development trunk for two developers.  The developers
develop.  One developer's code passed QA.  The other's did not.  I
would like to leave the first developer's code in the branch, but I'd
like to remove the other developer's code.  

Does anyone have any suggestions about what CVS function could offer me
some assistance in doing this?  If not, can you suggest how I could
better prepare in the future?