In order to add or remove or alter members listed on your filing and recorded by the state, you would need to file an Amendment to the Secretary of State. (some states the member or Director names may not be recorded onto your articles. If you do not see the names on your articles then no filing is needed and you would simply update your own internal documents/records)
If you have an account with us for the company in question then you can login at www.incfile.com/dashboard and go to the "STATE & IRS Filings" section and order the Amendment.
If you do not have an account with us for that business then you can order an amendment through our services here: https://www.incfile.com/manage-your-company/amendment/