How do you raise the handlebars on a mongoose 2.1 bike?

The Kruiser has a dead-ordinary quill stem. Loosen the center bolt(the one pointingstraight down the fork) a few turns, then give it a tap with a hammer or a mallet. That should disengage the wedge at the bottom of the stem, and with a bit of wiggling the stem should pull right up.

Take care not to raise the stem too high, or it might come out unintentionally. There should be a minimum insertion mark inscribed on the stem, ant that mark must remain hidden under the fork's locknut.