Follow each vine of the ivy down to the roots and cut it off with a pair of pruning shears. Use a pair of pruning loppers or a pruning saw to cut through the larger vines. Let the ivy attached to the vinyl siding dry out completely. The more dry and brittle the better. This may take a few weeks. When the leaves of the ivy crumble in your hand, it's probably dry enough to proceed with removal.
Climb a ladder to reach the parts of the vine highest on the wall. Locate the cup-like pads and gently scrape them off the siding with a stiff plastic putty knife. Don't pull out on the vine or you might damage the vinyl. Look for areas where the vines have grown into the joints between the vinyl panels. Cut the vine at these locations with a utility knife. Work your way down the wall until you have removed all of the ivy vines and cup-like pads.
Climb the ladder with a bottle of all-purpose cleaner and spray all of the adhesive residue left on the siding from the ivy's tendrils. Allow the cleaner to thoroughly saturate these areas. Scrub them with a stiff-bristled, nylon brush and then rinse the siding with a garden hose. Rinse from the top of the wall to the bottom. Do not spray the water upward or moisture will get behind the siding.