Firstly you will need set server nameservers for addon domain at your domain registrar. DNS propagation will take 12-24 hours.

1. Log into your cPanel account.
2. In the “Domains” section, click on “Addon Domains” Icon.
click on “Addon Domains” Icon, In the “Domains” section

chwkb-addon-domains-icon

3. Beneath “Remove Aliases”, locate the parked domain name and click on the “Remove” link.

chwkb-remove-addon-domain

4. For confirmation, you will need to hit once again on the “Remove Alias” button.

You will be able to a message that your Parked/Alias Domain is removed successfully.