I'm going to move out of my apartment without telling my friends
What makes you want to leave your apartment without telling anyone?
I want a chance since I've lived there for so long.
It is irresponsible to not inform your roommate that you are moving out.  Can they afford rent without your portion?  You should wait until the lease is up and you discuss it, too.
I don't want to tell them about it. I think I should be allowed to leave whenever I want. People can find me if they want to.
They can find you if they want to, that is true, but why can't you just tell them? They are your friends and you should be treating them like friends by telling them that you're leaving and where you are going.