functions.php

if ( ! is_admin() ) {
    add_filter(
        'query_vars',
        function ( $public_query_vars ) {

            foreach ( array( 'author', 'author_name' ) as $var ) {
                $key = array_search( $var, $public_query_vars );
                if ( false !== $key ) {
                    unset( $public_query_vars[$key] );
                }
            }

            return $public_query_vars;
        }
    );
}