Ok, so I'm a bronze 2 
main and I just got into my promos. I get into the game and my teammate bans nautilus. I didn't think he would ban a support so i didn't say i would play him. I was forced to use 
and everyone fed and we had a dc and lost. I'm really worried that I won't make my promos and I played some normals which I lost. How do I get off tilt?
play normal until you begin queueing with diamond III's and above. then you're sure to roflstomp everyone in ranked
but really, there's no way to get off tilt unless you believe you deserve the promotion and will carry the game.
Play a different game mode for fun, or take a break from league and play something else.
Take a break, play another game, go outside, talk to friends, watch or go see a movie, read a book, watch TV
My point being literally anything that will take your mind of League and puts you in a good mood. Then when you go back to League, don't concentrate on the stupid things that made you mad (but don't forget about them completely: learn from those mistakes and get better from them)
Stop playing, or play a match without giving a shit. ARAM, Bots, custom, whatever.
So when I'm ranking (more so when I'm nearing promos) I tend to literally just play a match. Win or lose, I go smoke a cigarette(or anything that just gives me a moment to breathe.) If I lost the match I'm often a bit upset or maybe even mad if there was a dc on our team or someone who afked for what ever reason. But I DONT want to go into another match being all pissy about the previous one. Even if we had a dc or afk, or someone who fed, I go over what I did wrong also that match or could of done better etc.
You just don't want to be in a bad mood when going into the que.
If you won the previous match then I normally just dive into the next, unless it was one 9 those close matches that had someone who just irked you the wrong way. For me that's tends to be good players with shitty attitudes. That's just me.
its simple, just stop tilting.
play the champions you like in normals/aram, play a bot match and beat up on some easy ai's until you go 40-0.
get a bunch of friends together and go do something in custom.
dont play league for 2 days.
the other option is to expand your champion pool, you cant reasonably expect to play the same role or get one of 2 champions every single game ever. you need to make compromises, you should know and have at least 3 champions per role/lane, that way you cant be banned out in a position you get "stuck" playing.
if you are really miserable and really hate playing with "bronzies" the only thing you can do is objectively look at yourself, ask "what should i be doing in games" "what did i do last game that i should do differently in my next game"
"why did i die to that gank" (was it because you were standing in the middle of the lane, or pushing the wave with auto attacks) ((or did they manage to land some long range abilities like a blitz pull or a sejuani ultimate)).
"why didn't i buy any wards at all on my first or second back and why didn't i place them in brush here and here "
you need to improve your playing if you want to leave bronzies.
stop caring
you stand up straight
listen to some uptown funk.... it ALWAYS healps... not even jking
