well first i make a refugium
then i sell the external filter on ebay
use that money to buy plants for my refugium
Now its clean.
As for your filter. As for any evil villainous overpriced under functional device of this nature.
Put the whole thing in a plastic 5 gallon home depot bucket, make a big old mess in there. so you can save the excess tank water for cleaning detritus off your components. a simple cut down rag tied to a coat hanger or even a weight on a string, drop it through the hoses. one good pull and its all gunk in the bucket. next you take the hoses out of the tank put them in the bucket with the external filter seal the bucket up and fill it with concrete bury it 30 feet under your yard and put up a sign warning people of potential radiation hazards.
Jokes aside, that's how its done, everyone has methods, towels tricks and little ways around the fact that an external filter is a sealed component and not actually a device that allows water to defy gravity.
Happy cleaning.
EDIT: If water is continually coming out of the hoses even after the disconnect its possible that you have a reverse siphon happening and water will just keep dumping out until you raise the hose ends above the water line in the tank.just lift quickly and try not to electrocute yourself please