4 on my Ti-84 Plus SE
But seriously, as strange as it sounds, your question is vague. Are you talking about 0 - (-2)^2 or 0 - -(2^2) or 0 (- -2)^2 , etc etc.
You need to know how your calculator works before you can use it. Depending on what the question is asking, I can get the 'right' answer.