on state tax form it is requiring retirement date i am 76 and still working

What state? Every state has different forms and rules. And where exactly is "it" requiring a retirement date? Is "it" an actual tax form, or is it a screen in the TurboTax interview? Where is it in the TurboTax interview? What is the exact question or title on the screen?

The "usual rule" is that if you retired from a job, but are still working some where else, you put the date you retired from the first job. But, as others have said, the actual rule is state specific.  

In addition to a reply, identifying the state, I suggest you edit the "subject" to include the state name. That should get more eyes on your question.