Disavow (verb)

1. Deny any responsibility or support for.
2. Refuse to acknowledge or accept the existence or validity of.

Origin:

Late middle english: from old french desavouer, based on latin dis- "away from" + advocare "call, summon".

Examples:

1. He was forced to disavow any connection with the group.
2. The company has consistently disavowed the allegations.
3. The country's leader disavowed the claims that his country was involved in the attack.
4. He disavowed the statement he had made earlier.
5. The government disavowed the treaty it had signed a year ago.