If you want to change your registered agent, you must file a Change of Registered Agent form with the state where the business is registered. Most states provide downloadable forms online on the Secretary of State's website. You can also request those forms in person.
Your state will require a “change registered agent” form and a form showing your new registered agent consents to being designated. Fill out and sign the forms, and your registered agent will have to do the same.
Once you've completed the forms, file them. Some states offer online filing, but you can also file the necessary documents by mail or in person. Check the exact requirements with the state where your business is registered.