Hah, I never thought of removing the shadow of an item, yet here you are to wake me up. Well, as far as I can see, you can't. If you are about to be moving this item via triggers, then you can make a custom unit for Neutral Passive and go to "Stats - Targeted as", untick all and then tick "Item". If you are not going to move it via triggers, make a custom destructible, remove its shadow (same goes to the unit solution) and Stats - Targeted as untick all and then tick "Item". Both cases let you cast the shadow you want on that and also give you the ability for that unit/destructible to be treated as an item. Then, implement a trigger that detects when a unit is issued an order targeting an object and when the unit is near the custom unit/destructible, use Hero - Create Item and give it to Unit.