Removing lights installed by previous owner

I would first try and locate the power source, see if you can identify the power wire at the switch with a test light. If it is active remove the two wires from the switch and test with the light, one will turn on the test light this will be the active wire, follow it back to find where it has been spliced into the positive power and terminate the connection. To do this it will depend on how it has been connected. If in doubt try and take a picture and post it here so I can see what has been done. With all power terminated you can remove the lights and wiring safely.