Honda headlamps and tail lamps are one piece assemblies. They are designed, sealed, and put together that way at the factory to eliminate the possibility of moisture, condensation, and premature burnout of lamps. You could break the assembly appart, but be prepared for a mess, and you probably won't get it back together the way it should be. People I know have tried to do that with the tail lamps for those stupid altezza modifications and other tacky things they do these days, only to find out they messed their assemblies up and can't put them back together tight.

My advice is this: if the yellowing bothers you enough to spend 250.00 to get rid of it, do it. If not, don't bother and leave it yellow.

Me personally I would spend the money to get a new assembly.