How to send Notice of revocation or renunciation? Revocation and renunciation may be expressed or implied? Section 206 and 207 of Indian Contract Act 1872
206. Reasonable notice must be given of such revocation or renunciation, otherwise the damage thereby resulting to the principal or the agent, as the case may be, must be made good to the one by the other.
207. Revocation and renunciation may be expressed or may be implied in the conduct of the principal or agent respectively.
A empowers B to let A's house. Afterwards A lets it himself. This is an implied revocation of B's authority.
Agent's duty to Principal
Principal's duty to agent