If you are designated an "authorized user" on a credit card, you have no legal obligation to pay the amounts due on that card. Period. You never signed a contract, it is not in your name, but strangely it does appear on your credit report. A lot of people mistakenly include this sort of information on a Bankruptcy petition, on Schedule F (unsecured debt).
Actually, as you only are an authorized user, you should not list the credit card as it is NOT your debt. If you or your attorney mistakenly list it, the credit card company will be notified of your Bankruptcy petition, and the credit grantor will be notified.
A better choice would be, prior to filing your Petition, contacting the credit grantor and taking your name off the account as an authorized user. Later, after your Discharge, you can always ask the principal on the account to put you back on, as if s/he is diligent in the payment on that account, THEIR record can and may well positively affect YOUR credit rating, which you will want to rebuild after discharging all of your debts.