What do you mean by "bottom pan?" I could interpret this to mean a bunch of different things...front undertray or maybe skidplate, oilpan, etc. More information would be helpful, or even a pic of what you're attempting to remove if you're not sure how to describe it.
The OEM skidplate is a no-brainer to remove, just take off the bolts and plastic bezels holding it in place. There isn't anything crazy holding it on, just lightly tug on it if you get stuck and you'll see what areas you missed.
Just remember that, most likely, when you pop those plastic retainers, there is a good chance they will break. 18 year old plastic hardens but if you are careful, you may get away without breaking them. Replacements can be found either on-line or at the dealer.
Depending on which ones break, you can always use zip ties instead.