(It's the middle of the three tubes you can see on the side)
Tube is held into both ends by friction of o-ring. End that is nearest also has a plastic clip to keep it on. Removed that plastic clip, then both ends are held in by friction. Removed tube by carefully pulling on nearest end until tube is loose. About the same for the other end... there is a small friction fork-like clip that it can be freed from before pulling out the tube in much the same manner as the other end.
Replacement is opposite of removal - a little grease on o-rings didn't seem to hurt either. (non-petroleum based, they're likely rubber)
No tools needed, but the tools listed were for removing dishwasher from under cabinet.