Originally Posted by Andrew R Stewart

Goldfinch- Sounds like your wife unthreaded the stem wedge bolt completely out of the wegde. Then the bulk of the stem will slide out of the steerer, but the wedge will remain. It is very possible that the wedge is stuck/rusted in place. If you turn over the bike, remove the ft wheel and any hardware that is going through the fork (say a reflector) you should be able to acess the wedge from below and tap it out through the top. Clean steerer and wedge up, lube all and reinstall so that the markings on the quill of the stem are at the headset's lock nut. (So the stem is inserted about 2 1/2"). That's the highest the stem can safely be set at. If she wants higher bar grip position then a stem or bars that are taller will be the option. Don't forget to check the cable's lengths if the controls end up a lot higher then stock.

While the stem and wheel are removed consider cleaning and lubing the headset bearings. Likely they are unserviced since factory assembly. Andy.