Is it one spirit, or are you seeing them everywhere like the kid in the 6th sense?
If it is the latter there are ways to shut off the abilty and turn it back on when you want to. Start off by closing your eyes, taking a deep breath, and remember that nothing can hurt you if you dont let it, while your eyes are closed firmly state that you want what ever you are seeing to be gone in the count of 3, count down and open your eyes. You need to reclaim your space, and remember that nothing can get too close if your stong and dont let it. Imagine a protective bubble of energy around your self, and use your own inner power to not let anything through it.
If it is one spirit, and more of a haunting demand that it goes away, again, reclaim your space. You are far more powerful than any human spirit.