Scòrdalo (you -sing.- forget)
Scordàtelo (you -pl.- forget)
If you want to add the person, you can transform it in:
Scòrdatelo (YOU -sing.- forget)
Scordàtevelo (YOU -pl.- forget)
But it isn't needful.
The verb is relatively correct, but "scordare" isn't a very graceful.
It's preferable to use "dimenticare":
Dimènticalo (sing.)
Dimenticàtelo (pl.)
If you want to add the person, again:
Dimènticatelo (sing.)
Dimenticàtelo (pl.)