I'm gonna steal someone else's 'advice'. I don't have anything for you if your siding is wood-based or vinyl but from reading the info on brick and masonry, I'm sure you can come up with a way to handle the aforementioned siding materials. If you have brick, and want to change the color or something, please don't ask me how to do it. (You might as well just leave the ivy.) Enjoy!
For brick: Ivy Removal. Ivy growth may be a contributing factor to moisture penetration. Ivy shoots, sometimes referred to as "suckers", penetrate voids in mortar and may conduct moisture into these voids. If this is the case, ivy removal may be necessary.
To effectively remove ivy, the vines should be carefully cut away from the wall. The vines should never be pulled from the wall as this could damage the brickwork. After cutting, the shoots will remain. These suckers should be left in the wall until they dry up and die. This usually takes from 2 to 3 weeks. Care should be taken not to allow the suckers to rot and oxidize as this could make them difficult to remove. Once the shoots die, the wall should be dampened and scrubbed with a stiff fiber brush and water. Laundry detergent or weed killer may be added to the water in small concentrations to aid in the removal of the shoots. If these additives are used, the wall must be thoroughly rinsed with clean water after scrubbing.
It is suggested that a small portion of the ivy (5-10 sq ft [0.5 to 1.0 m2]) be removed from an inconspicuous area first to determine how the masonry wall will appear once the ivy is removed. Tuck-pointing of the mortar joints may be necessary if the mortar has cracked or deteriorated.
For Masonry Walls: For an answer you have to weigh the advantages and disadvantages of ivy. Ivy can add to the beauty of masonry walls and give them some protection. It reduces temperature fluctuations by keeping the walls cooler in the summer. And the leaves shed rainwater, preventing large amounts of water from reaching the masonry.
In some cases, though, ivy can lead to moisture penetration problems or masonry deterioration. Ivy shoots can enter voids in mortar joints. Over time they can break up and dislodge mortar and masonry units. Ivy also can conduct moisture into walls and hold moisture against and within walls. This can contribute to efflorescence or moisture-related deterioration.
Whether or not ivy will cause significant deterioration depends on the quality of the materials and workmanship of the masonry walls. According to the Brick Institute of America (BIA), in a well-constructed wall made of quality materials, deterioration due to ivy may reduce the life of the wall by 10% at most (Engineering and Research Digest, May 1980).
Durability is not the only consideration, though. Ivy can provide homes for insects, birds, and other animals, which may then find ways to enter the building. Removing the ivy also may leave a defaced masonry wall. Depending on how deeply the shoots have penetrated the masonry, satisfactory removal of the ivy may be impossible. To evaluate the appearance of masonry after the ivy is removed, BIA recommends removing ivy from an inconspicuous area before removing it from the entire building.
If you decide to remove ivy, BIA recommends the following procedure. First, cut the ivy carefully away from the walls. Pulling the ivy from walls may damage the walls. Let the remaining ivy shoots die and dry out for 2 to 3 weeks. (Wait longer than 3 weeks and the shoots may rot and oxidize, making them difficult to remove.) Remove the dried shoots with a stiff brush and water. Add a small amount of laundry detergent to water to aid removal. If detergent is used, rinse the wall thoroughly with clean water afterward.