Quickest method to sell everything

I've built up a huge empire and have accumulated a sufficient fortune, but unfortunately (accidental pun) my empire is built on by-gone technologies that are limiting my profit potential (though it be the year 2022, my transport system is based primarily on rail, using far outdated engines).

Though the auto-replace feature makes upgrading my road vehicles easy, they are merely auxiliary to my train network which can not be upgraded so easily (I will have to rebuild all the track and stations and depots with monorail)

I've also found some deficiencies with my network on a very deep rooted, structural level, and am now looking to start over – removing all of my constructions and establishments whilst maintaining my wealth (rather than starting a new game).

Doing this the conventional way (the bulldozer) will take hours of tedious work, and I can't merely drag the bomb across the map (it would destroy the cities of which I've shaped the growth, and surely destroy my company's reputation).

What is the fastest approach to doing this kind of thing?
Will I have to send all my vehicles to depots, then sell them, then the depots, then all the stations and tracks?
Is there a button somewhere to do it all for me, or some kind of shortcut I can take?
Any bright ideas could save me a lot of time and work!

The people of Lartown thank you!