Model frt 15b3aw9 ser.ba61420703
Ican't remove the drain pan it sets in back on top of comp. (cabin on lake something in it died bad odor)
Seems loose but won't slide off

That model number doesn't tell us much. Can you better explain what appliance this is? Is it a frefigerator? I have a cabin on a lake, dead mice are a real pain.

Frigidaire refrigerator sorry really new at this thanks for any help afraid of breaking it

That is a drip pan for condensation, most are not removeable. I'd put a crevice toolof my shop vas or vacuum claner and fish around until you sag Mickey. If you can roll it out into the room you will see more from the back.

That unit usually has a nut or two in middle of pan that allows you to remove it. You need to get it out where you can see it. The best solution would be to vacuum it out and put a little bleach in it to clean it out because some units require you to remove bolts around bottom of refrigerator to drop the support for compressor and you need to be very careful you don't break something like a Freon line when you do this. Mice like to go in the pan and die when they are poisoned to get water.