If you have three people renting together, combine their incomes into one to see if it meets the 3x requirement.However, nothing is that easy.

I will not renew there lease, and I need to be better about enforcing the rules.

They offer credit, background, and eviction reports and make the process easy for both landlords and applicants.

There are rules to follow!

And I will state different jurisdictions have different rules, processes, expectations, etc.In my area you are required to have a permit to swap a water heater.

That is what the OP is wondering how he navigates those rules etc.

Sometimes occupants still live there and eviction is not easy, and I have even heard a story once that the yakuza are involved in the construction and real estate business and exorted money from buyers through occupants in these properties. 

Ok, but I mean is it against the rules?

There are rules to follow!

Take it easy i am still a rookie and trying to learn all things possible.