Robinhood and W8BEN for Non-US residents

I have an account with Robinhood which I opened when I was in the US and never traded on the platform. I did some trades this year. I am now an Indian resident for the entire year and forgot to close the account before moving to India and unfortunately i didn’t know that Robinhood was available only for US residents. It was a honest mistake and I am ready to pay any taxes or penalties applicable. I will close the account soon but want to know how to proceed to fix this mistake and can i send W8BEN form to Robinhood so they can withhold required amount if needed and i can file tax returns as non-resident next year. If i get 1099 next year can i still file my returns as 1040NR without claiming any tax exemptions?