ALWAYS consider common sense repairs before making a choice to demo and replace anything.

And can I get away with only getting permits on new electric & moving plumbing, but demo,  erect walls myself and things like that?

Unrelated to HOA but if homes won't pass the safety engineered designation, who demo's house and haul off and when does HOA or city make owner to remove?

But Now, in my area, not only does a plumber have to be the one that touches that, but I am "supposed" to hire a plumber just to demo (i.e. remove a toilet or vanity) the house. 

. $1,520.00•Demo about 12” of walls and rip out entire shower pan and step •Install cement board on exposed wall •Apply RedGuard and Waterproof membrane to shower pan and up the exposed walls •Install new drain adapter in shower floor •Install new tiles provided by client Optional (just in case fixing shower pan does not fix the water leak) rebuild shower. costs extra $5100•Demo shower • New plumbing for a new fixture •Install cement board on exposed wall •Apply RedGuard and Waterproof membrane to shower pan and up the exposed walls •Install new drain adapter in shower floor •Install new tiles provided by client •Client provides plumbing fixture

Had a great demo, but it's an awful large commitment to get set up with their services.

Quote from @Chengning Yang: I have an off market property currently for sale, and there's a potential buyer who wants to purchase it with cash. what should I do next?

If you want to chat or hop on a demo, feel free to connect with me!

You have no damages, though the previous owner at the time of demo may have had damages.3) Statute of limitation, if applicable, expires on nearly everything on civil matters at 3 years.

So you're the guy cleaning up the yard, trashing out the house, working the rehab or supervising the rehab, learn some of the work you could do without much time...paint, demo, basic repair, cleanup, etc.