I would send a formal written notice pointing out the violations and make it clear if they remain in violation you will either not renew the lease, if they are M2M, or begin the eviction process if they are on a term lease. 

That is unless you can show you are not prohibiting the future development of the remaining land),  general building setbacks or envelopes, storm pond/vault sizing, general utility layout, possible required improvements to frontage, required landscaping buffers, and more. 

I saw on the county's web page under the FAQs to request for a statement for the current-month purchase amount but do they ever relist the properties for a future auction, or once it reaches the List of Land available will it remain there until purchased?

Locally, they aren't underwriting 2019 NOIs until 2023...As the economy starts to reopen here we're seeing more signs of activity, but the future of local office space remains to be seen. 

Looking westward I’ve started to look more into Worcester since I’ve heard great success stories in this area.I’ve seen quite a bit posted by @Charlie MacPhearson describing the great deals in south shore.I’m currently in Andover so given I’m trying to stay north to remain closer to work, I am trying to look at Haverhill, Lowell, and Worcester.

The property was purchased and remains in my personal name.

Work with your remaining tenant.

It is the only entity structure whose rules allow the business owner to take a “reasonable salary” (subject to social security and medicare) and then take the remaining profit (often as much as 50% of the remaining income) out as distributions not subject to self-employment taxes.

I've gotten this request often and I allow it if I think the remaining person can afford the rent.  

As an example of #2 (the numbers may be very different than your situation, but the math is conceptually the same):10 Unit Apt Building, increase rents by $20 each year, assuming expenses remain the same.$20 x 10 units x 12 months = $2,400 in additional annual cash flow.At a 10% Cap Rate, this adds $24,000 in property value.With a 100 Unit building, the numbers are $24,000 in Cash Flow, $240,000 in added value.David Lindahl's 'Multi-Family Millions' book introduced me to this subject in a very easy to understand way.