J1-waiver

Hi,

       I'm scholar visitor with J-1 visa and want to get waiver.  I hear that J-1 visitor should stay North America to apply for the waiver, however,  unfortunately, I have to back China soon and not too much time to prepare the wavier. I have one question, could I apply F-1 or B2 visa back to United States and get J-1 waiver or I have to keep J-1 visa again to get waiver. 

Many thanks