I could not find clear guidance on changing a representative payee. I suggest having the new representative payee contact their nearest Social Security office. They likely will have to fill out form SSA-11. The office can help with the transfer. Here is a relevant excerpt :
You should contact the SSA office nearest you to apply to be a payee. You must then submit an application, form SSA-11 (Request to be selected as payee) and documents to prove your identity. You will need to provide your social security number or if you represent an organization, the organization’s employer identification number. SSA requires you to complete the payee application in a face-to-face interview (with certain exceptions).