Can you ever stop being emo?

For one thing, that person had no idea what she / he was talking about.

If you're a real emo it's your lifestyle. You can't just stop listening to real emo music and dressing in real emo fashion because you decide you don't want to anymore if that's actually who you are.

But I'm guessing you didn't know what emo was in the first place so if you're just depressed and self harming you weren't emo in the first place and you should stop labelling yourself that because it's wrong.

It's a teenage phase today anyway, you're going to grow out of it eventually.