Unable to unset Set-Cookie response header

[Luigi Bellio <luigi.bellio@xxxxxxxxx>]

    Hi all,
    
        we are using version 2.4.57 of Apache HTTPd with this
    configuration
>     <VirtualHost *:1080>
>                 ServerName <OMITTED>:1080
>                 CustomLog <OMITTED> combined
>                 ErrorLog <OMITTED>
>         
>                 DocumentRoot "/usr/local/apache2/conf/extra"
>         
>                 <Directory /usr/local/apache2/conf/extra>
>                     Require all granted
>                 </Directory>
>         
>                 ErrorDocument 502 <OMITTED>
>                 ErrorDocument 503 <OMITTED>
>         
>                 ProxyErrorOverride On
>         
>                 ProxyPass /favicon.ico !
>                 ProxyPass /error/ !
>         
>                 Header always unset Set-Cookie
>         
>                 ProxyPreserveHost On
>         
>                 ProxyPass / http://<OMITTED>:1080/
>                 ProxyPassReverse / http://<OMITTED>:1080/
>             </VirtualHost>
>     
        and the response header "Set-Cookie"
    returned by the proxied backend is not unset and is returned to
    client. What is missing?
    
        Thanks for your support?
    
        Luigi Bellio.