Is it wrong to pull the plug on someone who's not braindead?

For example, someone get into a car accident and ended up in a coma. He's not braindead, and you know he/she is gonna wake up from the coma and he's gonna be fine. Are you allowed to or is it wrong to pull the plug on someone who's not in a braindead coma?
Update: Just to clarify, I'm not in this situation of pulling the plug on someone. Its out of curiosity
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