IF you have a no turban then you are not a Sikh. It means Bhagat Kabeer ji, Baba Fareed ji, Shree Krishan ji, Bhagat Ravidas Ji etc not a Sikh.
I don't think you were intentional in guessing it so but a turban is one of the symbols (identities) of Sikhism and just that. If I am right, Sikhism doesn't discriminate against those who have shunned turbans