Maybe work at a large apartment complex in the rental office showing apartments and taking applications.That way you can get to know how to show units, proper safety techniques for yourself during a showing, and standard industry protocol for a lot of other things.And make some friends along the way.Pro Tip: They tend to put fresh cookies out in a lot of places--but staff are not allowed to eat them.

@Christopher Prince-BarryIf you’ve given them proper notice, and they don’t move out, file for eviction.

The Landlord can do it IF it is written into the lease agreement properly and they can remove the items without disturbing the peace.

Because of its location, I cannot have two proper units, but can have a main unit and an ADU or rent as one house (although I'm hoping the new development will bring a change to my zoning code) The basement has 8ft ceilings and is completely finished but I'm thinking of digging down behind the rear wall to add a full bedroom and reconfiguring the floor plan to accommodate another room, kitchen, and door to walkout (2 bed/1bath unit).

It also states that there is a $500 "re-rent fee" charged to all tenants who have not completed their full term, or who do not give proper 30 days notice.

What are the proper steps to take?

If you proceed with caution and screen potential tenants properly, then this should help in the long run.

If this is your first investment I would not recommend going through a wholesaler or an off market because like @Lucia Rushton mentioned you will not be properly represented in your transaction. 

Hiring a historic consultant would have paid for itself, doing proper work from day 1; funds for this expert must be in the budget.

This has been an ongoing issue since the beginning and I'm learning the hard way to screen tenants properly.