High beams stuck on?

At times when I turn on the high beams, they stay locked on and they won't turn off. I will turn on and off the lights, flip the switch on and off, wiggle it, and sometimes it turns it off and other times it just goes off. The low beams work all the time. Research I have done suggests replacing the high beam relay but I can't find it in the under the hood relay box. Unsure where to go from here.