How to Annul a Vow

Hello,

The process involves using regret as an opening, where one of the annulment authorities [there must be three individuals of understanding who comprehend what an opening and regret are, and ideally, the authorities should sit while the vow-taker stands] asks the vow-taker, 'Do you regret making the vow?' and he answers, 'Yes, I regret it.' Then they ask him, 'If you had known you would regret it, would you have made the vow?' and he answers, 'No, if I had known I would regret it, I would not have made the vow.' Then the three authorities say to him, 'It is permitted to you, it is permitted to you, it is permitted to you,' three times.

(Not every vow can be annulled, so when annulling a vow that is remembered, it is mandatory to specify the vow to at least one of the authorities).

Shulchan Aruch, Yoreh De'ah, Siman 228, Seif 7 and Rema there.