what are you trying to do / why do you need to remove it?
We recently had to repair the trans cooler lines on an OBD K2500 4x4. Absolutely no way thse lines are coming off the trans without dropping it ( trans ) out of the truck. The line had to be repaired, as the PO had cut them at the rad, and plumbed an additional cooler.
After the cooler and aftermarket rubber hose went in the bin, we "repaired" the line with a barbed hose fitting connected to the hard line with a compression fitting. It is holding up well, and will serve until the engine / trans is pulled for a completed rebuild. At that time we'll replace all the lines.
You will need a Mastercool brand tube flaring tool ( available on evilbay ) to form the GM flare ends, if / when replacing the hard lines. Flare nuts are available too, if you measure the line size and do a search.
I can post a pic of the repair if you need also..
Hope this helps.