39 year old from Solana Beach, CA
It appears that reverse mortgage servicer wants you to write a simply worded letter to them describing what you intend to do with the property (sell, refinance or otherwise payoff the reverse mortgage), as well as to request a certain amount of time to deal with the property. I would write both in one letter, say that your living in the home and will be selling it, and that you request an initial 4 to 6 months to prepare the home for sale, find a listing agent, and to give it an adequate (albeit initial) time on the market.
You can ask the mortgage holder for examples of the letters, and they'll assist you.
The actual Reverse Mortgage note informs the borrowers the Reverse Mortgage is due and payable 30 days after the last person on Title no longer occupies the home as their primary residence. However, they'll provide the Heirs up to 12 months if they're going to sell the property, thus the reason for them asking you for the letters.
**All above answers are provided as general information only. No warranty is made regarding the fitness or accuracy of the information provided in this answer. You should seek advice from a licensed CPA, attorney or CERTIFIED FINANCIAL PLANNER™ as to your unique financial situation.