Hello,I wanted to know from experienced investors how do you develop a solid offer letter without the use of a real estate agent?

Even if they have moved out, they are responsible for the rent until it is re-rented.I'm assuming you will be sending a letter with the accounting of their security deposit. 

You will likely have to sign a letter of explanation, but it won't prevent you from doing so.

You need to make sure there are no contingencies to an NFA ( no further action) letter if it is issued. 

Just last week I parked a rv in the back of a rental and they sent me a letter  saying I couldn't  park rv outside rv park even though alot of properties  have rvs parked on side of house or in back.

If I was new I would still have a quality buyer's agent I worked with, but would need the flexibility to offer solo on my own off-market finds.I use a letter of intent (LOI).  

Also, get the holes in the roof closed up and also trim all the trees that overhang the roof, that could be how the rats get up there.2- Tell your tenant that you are sorry, but it will be handled with his renter's insurance (which, if you have a good lease, it will say that he has to or should have it) FYI: outside or in the garage makes no difference here, it is HIS bike, not yours.3- Make letter (for documentation) about the poop outside and tell him that the poop is the cause of the problem, and that he has to clean that up or he will be evicted (I am sure there is a clause in your lease about maintenance and  keeping things hygienic.

However, I have been told by a MA mortgage banker that FHA and MassHousing will require a letter from HR stating that I am able to work remotely or that my move would not impair my employment status.

A few weeks ago, however, I started a yellow letter campaign with hand written (color copied), hand delivered, letters. 

My lender only required the person gifting me the money to write a letter stating that particular amount of money was a gift and had no expectation of being repaid back...