It would be disconnected and safe but it may be a conversation starter, or could be a neat historical feature.

There seems to be a disconnect here.

You can try Roofing.QualitySmith.com i found this with a quick search they offer an on line bidding system. you should ask the roofers if there insured, there experience in roofing, for some referrals also make sure to get several bids. a job like a roof has a lot of labor cost in it so bids will vary. id also get bids on the job with a tear off and an overlay. if your replacing the air cooler then the installer of the new unit should disconnect and remove it properly. roofers might brutally remove it and destroy mounts,connections or duct work and make more repairs for you. plus they may throw it off the roof Ive seen it done.

Why don't you disconnect service?

Knob & Tub is from the '20s and to replace that you will also need to replace the 'FUSE BOX' with a modern distribution box with disconnect. 

As also mentioned if you have your own you have to disconnect them, move them, store them and if they sit for a year they may not work in a year from now.

Ultimately it's important to move forward and if you want want closure I'd opt to speak to them to see what went wrong and where you felt like there's a disconnect and move on. 

Now I have not been an investor for long but I have been a business owner for over 20 years and I cannot make that disconnect so black and white.

They want a coach but a successful investor is averaging for instance thousands to tens of thousands per hour for returns & can't sit there and devote every waking second to getting someone's investment business off the ground.It's a big disconnect in the industry with expectations and what is being offered. 

My desperate next step is to disconnect Guesty and run my 4 (soon to be 6) Airbnbs purely on the Airbnb host page.