the quick google search I did shows that this brand are the sort of chiller you pump water through and back to the tank/sump with hoses. Is that correct?
If its on its own pump just shut it off and pull it, draining the water into buckets/bowls or back to the tank.
If it is inline with a sump return then a little more tricky, but if you are breaking the tank down for sale and transport, then as you drain it out and get it empty it should be just a matter of pulling the hoses off.