I was asked if I still work at a location and pressed no instead of yes. How do I go back and edit

This is OK.  It sounds like you just need to add the W-2 for that employer.  To do this, refer to the steps in the following Help Article:  Where do I add or enter a second W-2?

I have been filing my son's tax return on Turbo tax for many years I have done this twice as long as you have not transmitted your information it will give you a chance to go back and edit it

If you haven't already filed your return:

1. Open (continue) your return if you don't already have it open.
2. Search for W-2 and select the Jump to link in the search results.
3. We'll take you to a screen where you can click Add a W-2 for [your name or your spouse's name].
4. Enter the information from the new W-2 on the following screens.

If you have already e-filed, you'll have to wait until your return is either accepted or rejected.

• If rejected, you can add the W-2 as described above before resubmitting or paper-filing your return.
• If accepted (or if you have already paper-filed), you'll need to amend your return to add another W-2.