So, first thing to do in order to remove your diesel furnace is to find the fuel lines and the electric cables. There should be two flexible hoses for the diesel fuel: one is the supply and the other is the return. There should also be two wires (or a single cable with two conductors).
Trace the fuel lines back to their source and look for one or two shutoff valves. Trace the wires back to the electrical panel and look for the breaker or switch which disconnects them.
Lemme know what you find and we'll work from there.