Competition might be the only thing that's challenging you to get better.
Maybe you should seek it out and learn from it instead of complaining that it's there.
The competitor might be better than you, or even worse - doing the exact same thing you're doing.
So, instead of shutting down, how do you specialize even more, build a more loyal following, and do better work?
These are the questions that should be asked when competition happens. It's good for you.