Yes it should be away from the ceiling. The sulphur goes up before falling down and too close to the ceiling will cause a lot of vapor to just stuck to the ceiling.
Ideally the middle of the room is best, but if you do a long enough burn it doesn't really matter where it is too much. With plants I hang it about 2
or 3 feet above the canopy.
Beware though, sulphur burners can destroy some LED lights unless they are silicone coated
or using 301H diodes.