On the flip side, how do you end a startup? (gracefully)
Pay off the debt.
In addition to all the normal, expected stuff (eg turning off the light switches), find someone to facilitate a “saying good bye” conversation for all the major contributors. Even if this means journaling to themselves.
I’ve instituted this at DayJob. 10 questions, getting at what worked, what didn’t, and why stopping is the best answer.