Here is a listing from Mpls' webpage, a bedroom must be 70 square feet: https://www2.minneapolismn.gov/business-services/licenses-permits/construction-permits-certificates/building-requirements/habitable-room-definitions/  The definition doesn't list 7 feet but anything under 7 feet would probably be looked at as a closet by most people looking to live there.  

It is not worth the energy and expense to try to enforce the lease, the only leverage you have is harming their credit, which they don't care about right after a home purchase. 

Just imagine what will happen once the habit is formed.

I told the tenant that I would need to call this property uninhabitable (since she had screamed at me about how the mold and bacteria from the sewage water can harm herself and her child) and asked her to find herself alternate accommodations.

They will need to be interested in basically being a landlord till the tenant buyer gets a bank loan.ANOTHER area new folks get wrong and harms the tenant buyer is the option fee is not handled or contracted correctly for the eventual financing bank to include the option fee paid to be included in the down payment. 

Well his credit and spending habits allowed him to borrow foe a $105K boat and a car .

@Lukas Ku just wanted to point out that by code, a habitable living area should have a minimum of 70 sq ft with a minimum width of 7 feet in one direction.

Being undercapitalized, not having money to make needed time sensitive repairs, so they have to take drastic action to meet habitability requirements. 

We do this out of habit when we find an awesome book.  

We don’t know any PMCs to recommend in the area mentioned, but since selecting the wrong PMC is usually more harmful than selecting a bad tenant, you might want to read our series about “How to Screen a PMC Better than a Tenant”:https://www.biggerpockets.com/member-blogs/3094/91877-how-to-screen-a-pmc-better-than-a-tenant-part-1-services-and-processesWe recommend you get management contracts from several PMCs and compare the services they cover and, more importantly, what they each DO NOT cover.