For controllers, it's easy. Just press the confirmation button (usually X or A, depending how your contoller is set up), and it'll drop it for you right where you stand. xD

Bascially, the same button you used to select and pick it up, is the same button you will use to put it down ^^

If you want to practice or verify, can always unsync Copperbell HM and use the bombs on Biggy to get a feel for it! (Since it was mentioned, lol)