You can use the Troll Camp:
While Troll Camp is in play, Bilbo Baggins gains: "Action: Exhaust Bilbo Baggins and spend 1 [Baggins] resource to remove 1 sack card from a character. Bilbo Baggins may trigger this effect even with a Sack card attached to him."
Just don't make the mistake of letting Bilbo get sacked while he's exhausted like my partner and I did. Then you'll never get rid of them!