should I attempt to disconnect old propane generator or hire someone?

Hey guys I recently sold an old propane generator that's in my family's Warehouse and the guy is driving a long distance to pick it up so I'm s rambling to get in unhooked. I have disconnected the exhaust and propane line and now I'm looking at the electrical. I thought it would be as simple as disconnecting the wires after I shut off the main breaker to the building but my father mentioned that one time when he turned off the switch to the generator one of the tenants power also went out so now I'm worried if I simply disconnect the wires that I will be starting something that I may not be able to fix and since I cannot have the power out for more than an hour or so I'm having second thoughts. Is this something I should attempt to do on my own? is it wired like a switch with incoming and outgoing wires and I just have to bypass the generator and connect the wires or is this more complicated than my basic electrical knowledge and I should really be hiring a professional? any help would be very greatly appreciated as I only have another day or two to get this done!