How to satisfy demand for low income housing in Sim City 4 in a wealthy city?

One method I used to take care of this (I used to make the mistake of confusing low income with low density) was to create residential housing zones in the lesser desirable parts of town, like near the landfills, power plants, etc. The desire for this area will be low, but the lower income residents would still move there, where the higher income residents would stay in the more desirable parts of the city.

Side note, it's been a long time since I've done that, so I'm not sure if the mechanics are the same now or not. (if that's not the case any longer, I'll be glad to delete my answer.)

If you just want to get rid of the demand for low income housing and encourage wealthier people to move in, raise your taxes on low income residential to punitive levels. If taxes are too high, demand for that type of zone will fall.