SSA retirement benefits and 1040NR

What is your status in the US?  Are you a US resident alien or a nonresident alien living in the US?

I am non-resident. I live in Canada and I am Canadian. I worked two years in USA

Since you are a Canadian resident, not living or working in the US, then you only need to file a Canadian tax return.  The US Social Security benefits you receive is reported on your Canadian tax return along with the income received from a US IRA or other US tax deferred retirement account.