Be ledge cancel you mean UpB from on stage onto edge of stage?
Techinically, no.
Zelda is standing when she comes out of her teleport and so momentum is able to shove her off the ledge before the flashy twirly lights have time to finish. Sheik tends to land at weird angles since she likes to flip while vanishing. Ultimately, yes, you can teleport on to the edge and go over the side, but the uses for this don't go farther than falling off the stage. If you do it right you grab the ledge, if you miss you die. Clearly not as useful as Zeldas.
<3, I don't understand how you find it more useful than Zelda's ledgewarp. She can do ANY move with zero landing lag out of a teleport. Iirc not even MK can do that.
Ledgewarping is quite easy.
1. Teeter at edge
2. Teleport towards center of stage at any angle you wish.
3. Take ONE small step towards the ledge you were just at.
4. Teleport back at the same angle as step 2.
All you have to do is mark the place you got to at step 3 on whatever stage you want and easy ledgewarping from there.
If you were referring to something else, Char, then I think you mean vanishing while leveled with the stage, right next to the edge -- as in not grabbing the ledge as you get within grabbing range.
Yeah, you can do that too. Hold down or away from the stage as you approach the ledge in part one of the Vanish, then hold towards the ledge. Sheik will explode right next to the ledge and then grab it, instead of cancelling the explosion and just grabbing the ledge. This is quite useful for punishing bad edgeguarding, and it's very likely to kill if the enemy is at high %ages.