OK, if DustinV is correct, you can try this. Leave the CPU and fan system mounted in the socket with the lock arm down. Loosen just the screws and nuts that hold down the heatsink. Now GENTLY try to twist the heatsink while the CPU chip itself is held securely by the socket. If you can get it to twist both ways, that will loosen the bond of heatsink to chip so that you can remove it.
If it will twist but still not lift up, then stop lifting. Unlock the lever and pull out the entire heatsink and CPU chip. Gently use a wedge or screwdriver to try to pry the edge of the CPU loose from the heatsink, and then separate them. Be very careful not to scratch the heatsink surface since I suspect you plan to re-use it. Likewise, try not to scratch the CPU surface either just in case you want to re-use that some time.