Abjure (verb)

To renounce, reject or abandon formally, publicly or solemnly.

Origin:

From latin abjurare, from ab- "away" + jurare "to swear".

Examples:

1. He abjured his former beliefs and joined a new faith.
2. The king abjured his claim to the throne.
3. She had to abjure her former ways and adopt new customs.
4. The witness was forced to abjure his testimony.
5. He abjured his allegiance to the rebel group.