Overview
To edit the httpd.conf or apache2.config file, you must have a Dedicated server with an admin user.
Admin access is not available on VPS machines.
Checking the version of Ubuntu
The location of the server's config file is different depending on which version of Ubuntu is running. You can manually check which version is running via SSH.
The following command confirms the server is still running Ubuntu 14.
[server]$ cat /etc/issue Ubuntu 14.04.5 LTS \n \l
And this shows a server running Ubuntu 18.
[server]$ cat /etc/issue Ubuntu 18.04.1 LTS \n \l
Location of the httpd.conf file (Ubuntu 14 (Trusty) machines only)
If your Dedicated server is running Ubuntu 14 (Trusty), you can find this file in the following location:
/dh/apache2/httpd-INSTANCE/etc/httpd.conf
Location of the apache2.conf file (Ubuntu 18 (Bionic) machines only)
If your Dedicated server is running Ubuntu 18 (Bionic), you can find this file in the following location:
/etc/apache2-httpd-INSTANCE/apache2.conf