Do I need to cancel the lawyer's power of attorney in court?

Don't. a lawyer's power of attorney is a certificate of authorization submitted by the client to the law firm when the client entrusts a lawyer to represent the client in litigation, indicating that the lawyer can conduct litigation activities on behalf of the client. According to Article 934 of the Civil Law of People's Republic of China (PRC), if the client dies or terminates, or the agent dies or loses capacity for civil conduct or terminates, the entrustment shall be terminated.