Use this useful tool to convert angular acceleration choosing one of the 15 units of measurment included in this app (with the availability to add custom units), that are:
radian/square second, radian/square minute, revolution/square second, revolution/minute/second, revolution/square minute, cycle/square hour, cycle/square minute, cycle/square second, cycle/square millisecond, degree/square hour, degree/square minute, degree/square second, radian/square hour, radian/square millisecond, degree/square millisecond.