My prior vehicle had rear drum rear brakes and was only driven occasionally. The shoes would seize to the drums after driving in the rain and then sitting - this may be your problem if you have drum brakes in the rear. Never had a problem with the front discs.

 

Parking brake lever is loose because parking brake siezed
When shoes dont retract back you have slack in parking brake cable
Have you tried moving driving the car anyway?
Previous car brakes would sieze from sitting

I would force it loose by driving
You will hear grinding and moaning as it loosens

 

Can't get it to budge by driving. Tried 4x4 lock and esp off no luck. I tried towing it with my truck but the back wheels still won't budge just dragged it over the driveway for a few yards. Front wheels are not seized up.

 

2 things come to mind.

Parking brake cable/s are seized. You can try disconnecting the cables at the rear brake calipers.

Brake caliper piston/s are seized, you will have to try to retract piston/s by opening the bleeder screw and prying the pads back with a screwdriver.

 

It ended up being the springs on the parking brake shoes. The springs were so rusted they would not retract. I ended up removing the rotors, spraying some wd40 on the springs and lightly tapped on the shoes with a small hammer. It eventually loosened up to the point that my parking brake lever starting working again and the shoes would expand and retract. I had to do the same thing on both rear wheels. I was able to move the vehicle after that with out issues. I plan on replacing the shoes and spring components. Thanks for the tips and suggestions.