I have a F350 that I bought used and I believe that it has a HID kit installed on it. I say this because I cannot get the high beams to work and the fog lights will not come on. I have been told that it is a plug in and will be easy to remove. Is this correct?

The bulbs are brighter YES....but I want to take it back to stock and get new lense covers later.

 

All you should have to do is unplug the
connectors where the harness plugs into and reinstall the incandescent
lamps of the right type. Look around the back side of the lamp housing
for some extra boxes that lead to the lamps and that will be the ballasts
one for each side. Use care when you remove and don't get fingers on the lamps
someone most likely will be willing to buy them from you.
Her is a diagram of what you may have

There is more info on there page at
HID Kit Installation Guide
In looking at there page it has a lot of good info on HID and can be useful for
removing what you have and returning back to stock.

Sean