Outlet drain hose of my washing machine must go all the way to the top of the machine?
I believe you want this in place, so before removing it, I'd check with the manufacturer to see if they permit it. I can think of at least three reasons you'd want the drain line secured at this height:


Drain hoses for appliances like dishwashers and washing machines that run into a sink drain are installed above, or as close to the top of the sink drain to ensure any clog in the sink backs into the sink itself, and not siphoned into the nearby dishwasher or washing machine. You don't want to find waste from the sink in the bottom of your washing machine.
You also need this line above the high water level of the washing machine so it doesn't siphon out while washing.
Keeping the high point of the line immediately adjacent to the machine with these security clips reduces the effort of the pump and how much water may drain back into the machine after it completes its wash cycle. The manufacturer will have a better understanding of their pump's requirements.