I am on F1 visa and I need to amend my prior year returns. I filed 1040instead of 1040 NR. How do I amend these returns. Is there any software that will allow me to do so

The following instructions for the F1040X are designed to answer your question.

"Use Form 1040X to amend Form 1040NR or Form 1040NR-EZ. Also, use Form 1040X if you should have filed Form 1040, 1040A, or 1040EZ instead of Form 1040NR or 1040NR-EZ, or vice versa.

To amend Form 1040NR or 1040NR-EZ or to file the correct return, fill in your name, address, and social security number (SSN) or IRS individual taxpayer identification number (ITIN) on Form 1040X. Also complete line C, explaining why you are making the change.

Attach the corrected return (Form 1040, Form 1040NR, etc.) to Form 1040X. Across the top of the corrected return, enter “Amended.” "

I know of no software that does this correction. But there may be some.