1st Domains will show a parking page for your domain name if there is no active web site or URL redirection in place. The parking page can be disabled with the following steps:
1) Firstly, login to the Account Manager and select 'Manage Domains & Services'
2) Next select the domain name you wish to manage.
3) Click on 'Manage DNS Zone Records'
4) Delete the DNS records that are tagged with [Parking] next to them.
The parking page will now be disabled within 1 hours. If you are still seeing the parking page, it you may have a cached result on your browser. Clearing the cache on that browser should resolve the issue.