First of all, never tell anyone that you're muting them.
Why would you say that to someone ? Because you want to politely inform them that you are not pleased with their communication ?
NO! You just want to show your power. You want to feel better and tell yourself you won that argument.
Just mute people, after some time, they'll realise that they are talking into empty space. This will just make them feel stupid.
Enough with the advice you didn't ask for.
You know, you don't get a warning because of one game. If the game detects that your amounts of reports have increased, you'll get informed that you should improve your behavior. Isn't that a nice thing from Riot?
If you really didn't do anything wrong that game, you don't have to care about reports.
Fake reports won't get you a punishment.
Apparently you didn't like your teammates in the first game. It would be smart to just wait a little before you jump into the next game.
This would decrease the chance of having the same people in your team and you'll be less frustrated in the next game.
Have a nice day,
-Torpedosheep