give it a good blast with WD40 first,

then prise the clip off with a flat blade screwdriver, then hold the end of the rubber hose with a spanner, prolly 15mm, then undo the brake union on the metal pipe

this will just spin until its undone, then pull the rubber hose out of its location downwards.

BE CAREFUL TO NOT ROUND OFF THE UNION THO!

very easily done if its been in place for years