Yes, she can learn how to turn it off at will. You'll need to look around for people who teach that sort of thing and make sure they are legit.

I grew up with a girl who saw spirits all her life. She never told me until she was in college, but she grew up very fearful because she always saw the dead. She said most nights she'd have to hide under her covers. Then she sought help on how to turn it off and on at will from some sort of psychic group. And it worked for her.