2 Answers

Hire a contractor. We are a general questions and answer forum. We would have to see how it is installed to tell you how to safely uninstall it. 

   At the outside unit (Condensor there are two Copper lines coming out at the bottomm right before they leave the Unit there are valves. unscrew both and get a allen wrench that will fit into each. The 3/8 copper valve you need to tighten all the down into the valve. Then turn the Unit on. Give it 3-5 min. Now tighten the other bigger Valve.

 Now you Can cut the copper with a copper cutter after turning all the power off and disconnecting it. remove Unit. Make sure the Indoor is off before you disconnect the 5 smaller wires (brown)  these are the t stat and if they touch any medal will blow a fuse and  make for a long day if it actually lets the smoke out of the transformer in the inside unit.

  You can also remove the indoor unit as well after cutting copper, drain lines, power