While replacing my radiator I was able to unscrew this front the top, but am unable to access the bottom. How do I remove the transmission lines from the radiator adapter?

 

I just did mine not too long ago.... and like everything else on these "god forsaken-pita trucks, you have to remove about 20 other parts until you CAN get into it.

 

Did you need any special tools to separate them?

 

As you likely found the tank fitting performs a seal between the tank and the cooler coil.
The line fitting is special in that it and the line is configured to use an O ring seal inside the fitting not a taper seal or compression.
Take the tank top holders off and rise the tank a bit to get at the lower fitting.
There are special wrenches with open slot ends for working on tube fittings.
Good luck.