It's am3, so it has a retaining bar across the CPU socket, one of the sides would have a release lever or mechanism to unlock the cooler from the motherboard.
Problem with this is that quite often, the thermal paste has cured enough to act as a glue, making the cooler stick to the CPU.
Twisting the cooler slightly in clockwise or counter clockwise direction usually breaks this bond, allowing you to pull the cooler out without risking damage to cpu pins.
so:
1. find the cooler retaining latch. (it is quite likely visible on all but 1st picture
2. unlock latch, make sure that the cooler is no longer locked on the MB (there are those white plastic locking tabs through MB on 2-5th picture that might require you to take off the whole MB to get them out.)
3. twist the cooler a bit to break the thermal paste bond
4. pull cooler out
see point 2 about possible extra locking pins, twisting cooler while they are still in place is a bad idea.