How do you adjust the height on a motorcycle?

I assume that you need to lower the height, since most bikes have plenty of suspension. If you are referring to seat height, you can cut the foam down or I believe the company name is Tru Technologies offers lowered subframes. As far as the suspension goes, several companies make lowering links. Another option is to have a suspension shop shorten the forks and shock together which lowers the bike the same front and rear (you do lose an inch or two of suspension travel, but you do when you use sag or the link as well). This keeps the geometry and handling the same. Its also reversable if the person gets taller or you want to sell the bike.