How to turn off inside (dome light) in 1992 buick skylark

The headlight switch will either have a rotory knob that dims and brightens the instrument lights. When the instruments lights are at their brightest, just past that the dome light will come on. Back that off just a bit (you should feel it click). If it has no rotary knob then its in the pull switch that turns the headlights on. Twist that knob counter clockwise.

If that is not the issue then there may be a door jamb switch that needs adjusting.
Open a door and push on the door jamb switch (usually located near the front of the door area by the hinges). If it still does not go off then try another door until you find the one that makes it go off.
Then, with some pliers, grab the button and gently pull out. The button is inside of a sleeve and that sleeve moves in and out of the part that screws into the body. When you close the door it will push the button and sleeve in as far as it needs to go.

then if that is not it there is a wire for the dome light grounding. The interior lights have constant power and it is the ground that opens and closes to turn the light on and off.