Thank you for your reply.
I have, however, already thought of that. The root user does not have a cPanel account, and neither am I allowed to create a new one for the domain name "main.url" because the domain name is already taken by - you guessed it - WHM. Here is the error message:
It would not be wise to delete the main domain name from the DNS cluster. How would I then access WHM?
Account Creation Status: failed (Sorry, a DNS entry for main.url already exists, please delete it first (from all servers in the dns cluster) )
Why does the cPanel login screen show up at all when navigating to https://main.url:2083?