Outta is an easier way of saying out of. It's very common casual/informal English. even though when spelled out its longer, it's a short way of saying it. Similar to gotta which is a short way of saying "got to". For example " I've gotta get outta here! " - I've got to get out of here! (I need to leave)

I’m outta here. Out of here, slang meaning of out of here. Very colloquial, never use with teachers, or formal only with friends. Peace! I’m outta here! Get that dog outta here! Are you outta your mind! She’s only 15 years old!

Informal way to say out of

Out of

It means "out of"