How do you remove a radio in a 1998 Sunfire?

I think your '98 is like my '96. If so, here's what you do.

IF you have an auto transmission, set the parking brake or block the wheels. If you have a manual transmission, put it in 2nd or 4th gear. (this will become clearer later)

Gather a couple of screwdrivers and have a seat in the passenger side of the car.

Open the glove box. There is a little stop which keeps the glove box door from dropping

all the way to the floor. Locate that and bend it slightly so the door WILL drop to the floor.

With the door all the way down, you should be able to see a couple of screws that hold the molding around the radio to the dash. Remove these screws so you can pull that molding away and off. Here's where the transmission procedure above comes into play. With the car in PARK or in 1st or 3rd gear, the molding will most likely hit the shifter, making it difficult to remove. Having the shifter out of the way is a good thing.

Now, you should be able to see 4 (I think) screws that hold the radio to the dash. Remove these screws.

You should be able to pull the radio straight out toward the rear of the car. Don't pull too far or too fast though. There are two electrical connectors that need to be unplugged. Take care here, as there are locking tabs on the connectors which are easily broken. You'll also have to unplug the antenna.

Once everything is unplugged, the radio should just fall out into your waiting hands. As you might imagine, installation is just the reverse.

NOTE: pay attention to the anti theft feature of the radio. If you don't know your pass code, you might not be able to get the radio (or a replacement) working without a trip to your GM dealership. OR, you can snoop around on Ebay. There are sellers there, who will sell you the information on how to work around the pass code. It's worth the $5 or $10 they ask, to get the radio working again.