If you no longer have access to your phone and don't have your recovery code, you'll need the assistance of Steam Support. Use the "Help me with my issue" button at the top right of the page bellow to get help removing your authenticator. If you don’t have access to the email address that is currently associated with your Steam Account please provide proof of account ownership within your ticket.

https://psteamhelp.yuanyoumao.com/en/