I got IT. I can't do it alone...
sure you can... just bully it into submission like any normal teenager going through highschool picking on the outsider.
Depends if it's movie IT or Novel IT. With the Novel version, you'd not have a chance. In the novel, IT is essentially an evil (and very lazy) version of Q from Star Trek, being omnipotent and not dependent on you being scared to kill you, and the kids are only special because they have help from outside forces beyond this universe and no amount of belief would have saved them if they weren't hearded by outside forces unknown to them.
Your only absolute chance of defeating IT (from the novel) tempoarily is to know the weaknesses of whatever you're afraid of and exploit those (UV light for a Vampire, Silver for a Werewolf etc) to surprise IT into running away. That's if of course, you fear somethings supernatural. xD
Or of course, if you have no tangible fear, otherwise It'll just have to take over the minds of some Trump supporters to physically murder you and make it look like a hate crime or something.
With the Film version, I prefer MattPat's interpretation of the end of Chapter 2. Which makes way more sense than the whole "bullying to death" interpretation.