You can, but you need to lever it off which isn't really good cas you can strach the cpu, unless you use a a rubber thing of sumin. But you still can take it off.
Yes, I agree. You absolutely can take off the heatsink again. It's very easy. If the thermal compound is warm (right after you turn off your PC), then using a twisting motion of the heatsink will slide right off easily, assuming the retention springs are off.