I am trying to take off the switches in my 190E 2.3-16 for the seat so I can clean the contacts behind them. But after I take the buttons off, there is a plastic hollow post that is used by the seat reclining switch that wont allow the plastic backing to be removed. How do I remove that hollow post?

On my 1983 300SD, that hollow post was part of the seat switch. I had to remove the door skin to get to two screws that held the switch to the door sheetmetal. Not a fun job, as I ended up breaking the new $60 seat switch trying to get the door panel back on. Not sure if your car is the same.

Replacing the switch is the best remedy.
I would suggest replacing the switch without removing the door panel. If you unbolt the inner door handle so that you have room slide the seat switch in. I use a magnetic screwdriver so the the screw does not drop into the door, because then you do have to remove the door panel.

------------------