According to Osho, when Krishna wants Arjuna to disappear, he means the vanishing of Arjuna’s ego-bound personality—his doubts, ignorance, and sick mind—so that the hidden consciousness can flower and move, by any fitting path, toward liberation, like a river reaching the ocean. Krishna unveils all paths without choosing; Arjuna must choose, and in true choosing the false ‘Arjuna’ dissolves into the supreme.
It means Krishna wants Arjuna’s stubborn “me” to fade so his real self can flow into peace, like a river into the sea.