Anyone who is a biblical literalist will reject the concept of annulment of oaths. However, Jews accept this tradition as having been given to Moses on Mount Sinai. Taking oaths is a worthy way of inducing oneself to act properly. Because of the power of an oath, it is an extremely useful psychological motivator. Only these oaths can be nullified.
Oaths involving more than one person require both to be present and to agree to the annulment.
However, if someone else induced one to vow or swear this annulment does not help at all. Think about it. The Talmud dedicates one sixth of itself to detailing the Jewish court system which adjudicates based on the sworn testimony of witnesses. Any oath taken with others in mind cannot be nullified without their presence and approval. Even if the inducer is a child or a gentile the court does not annul it except before him so that he will know that the oath was annulled.