Get your taxes done using TurboTax

I just did this myself changing to non-dependent. Here's where you can get to the amend form for 1040x.

First screenshot is desktop site lower right corner, second is mobile version. Hope this helps!

Edit: for federal there is no box to check it uncheck, it'll just ask the reason why and I put changing as non-dependent. When you review the form look for the paragraph lines for "reason".

Your state might have a checkbox, it depends?