You can wipe over the ice with a cloth or towel soaked in hot water.
This will soften the ice enough so that it can be scraped off. A plastic
lifter like the type which is used with non stick frying is useful for
getting in under the ice and prying it off. Don't use metal scrapers if
the inner surface of your freezer has a foil coating as it can lead to
damage. A basin of boiling water placed at the bottom of a chest freezer
also helps to accelerate the melting of ice (After having pulled the
plug and removing all food)