Is it Part '9' below? -- The "Clamp" assembly? If so, you will need to separate it. If it's the hose below at the end of the elbow, after the clamp is off, then you should be able to treat it like a hose and go at it. Is it wire reinforced hose or just rubber?

I would think that you should either remove the elbow from the "rear" of the coolant reservoir or leave it in try and work the hose. But I wouldn't work on releasing that hose it HIHO? (Halfway-in-halfway-out). I'd worry about stripping the screws/bolt holes, etc.. and having to use heli-coils to put them back together.