Most seller financing has a 2-5 year term in my experience, though it can be whatever you agree upon.

Typically, in this situation, I advise my property management clients (in Florida) to terminate the month-to-month tenancy of a tenant who is causing problems like this and to place a better tenant in the unit.As for the tenant who is requesting to get out of their lease, of course, you do not have to release them from a lease term on that basis, but look to your lease and state laws regarding their ability to terminate the lease (whether a lease term or month-to-month).

Best action is to document an early termination agreement. 

or terminate the lease?

They will likely terminate before the inspection period expires.

If they caused you damages due to their violations of rules governing licensed brokers, you may be able to make a claim through the Real Estate Recovery Fund.2) either you or your attorney send an official termination of services letter (if you haven't already), wherein you need to demand that they remove listings, return to you your property they are holding, disburse your money to you by a date certain. 3) if they fail to comply with your demand, contact an attorney to prosecute the remedy.You can attempt to re-list your property yourself or with a new management company, but you may run into problems with listing websites when they see an existing listing for the same property.

The 10% to 18% cost of the DST would be repeated every time the DST terminates and a new 1031 exchange must be made into a new DST, maybe every 5 to 8 years, whereas the capital gains tax could be a one time cost.

I once spent all night pumping 3 feet of water out of a basement, in a monsoon, using a DC pump attached to my truck battery because there was no electricity to the house and the sump pump couldn't work.

All that says is that the policyholders stopped paying and terminated their policies. 

The model worked well for about 6 months and so on but went south after the strike and there were lot of cancellations and schedule changes so he eventually decided to terminate his lease.