/gamemode a
You can only turn off the rain if cheats are enabled. If they are, the command is /toggledownfall
You press E or Escape on the keyboard.
turn off the firewall is all you can do.
change your render distance on to tiny turn particles off and smooth lighting off
u get a redstone trail connected to it and a lever/button/pushplate an then step on the push plate/push the button/pull the lever and it will turn off.