Recalling?!?

Hello! If your defending from an attack can you recall?

if you mean once the battle has started, then no.

If you're the attacker you can recall troops (withdraw) by going to action --> command --> select any one of your troops --> withdraw. It costs 5 coins but your troops will return to your city and you won't lose any prestige. You won't gain any either.
You can't withdraw troops while defending.