In addition you want to know what condition your high cost repair items are in.  

The rents are way under market so I decided to send non-renewal letters with almost 60 days notice and offer a lease of my own explaining the current rental market conditions, and current going-rate prices.

Now, on the other hand, if the tenant is lying and the home is in excellent condition and you have the COC then yes, you can hire a lawyer and take other actions. 

I am not sure what condition the buildings are in though.

They are causing huge disturbance by doing drub and trashing the place to the worst condition you can imagine.

I am a realtor in the area and would be happy to send you some examples of successful STR's up here, and what the market conditions currently look like. 

Was already in great condition.

Depends completely on the condition of the property.

Most buildings that i've been finding right now are not accepting FHA financing due to the either the condition of the property OR because there are tenants residing the entire building. 

The tax assessor started asking me all sorts of questions about the current condition of the property (what renovations had we done, did we have any tenants, did we plan on having any tenants, etc).