International Student Amend Tax Return Non Filer

I am an International Student(F1) and I mistakenly filed the Non filer tool and It got approved for the year 2019.

I want to fix it now ...not sure how to do it.

I have received 2 stimulus checks which I dont think I am eligible for therefore I have mailed them beck to the IRS but I also want amend my returns for 2019. Please help!