Yes, you can amend your return. Per the 1040-X Instructions: "Resident and nonresident aliens. Use Form 1040X to amend Form 1040NR or Form 1040NR-EZ. Also, use Form 1040X if you should have filed Form 1040 (or, for years before 2018, Form 1040, 1040A, or 1040EZ) instead of Form 1040NR or 1040NR-EZ, or vice versa.
To start your amended return, go back into TurboTax, open the return that you already sent in, and on the first page you see, click on the link to amend your return.
