@Phil ********
Now we're getting some where.
You are on an extension of stay, SO to change the "reason" for your extension from one based on education to one based on being over 50 (retirement) you would
Take a letter from your school to the immigration office stating you are stopping studying on the day your current extension expires
the immigration office would cancel your existing extension AND then you would immediately apply for a new yearly extension based on being over 50 (retirement) by meeting the proof of financials and by supplying the correct documentation.
I have seen several people successfully go from an ED extension to one based on retirement without issues IF they have all the documentation and meet the proof of financials for the retirement extension..