vex iq competition

I am in 6th grade. I have a vex IQ kit. Can I participate in a competition by myself?

Yes, but it really helps if you have a codriver for matches.

Actually, you really need the second driver. The rules state that one driver can’t operate the robot for more than 35s, so every team needs at least 2 drivers for reasonable participation in tournaments.
But you don’t need any official organization backing you (like a school). You can declare a neighbourhood team and register with few friends. You still need an adult to sign you up, cover the fees and sign the release form at the tournament.