Now I can see a 403 Forbidden page instead of the Welcome page of this hosting. Try uploading a index.html on it and see how it works, and if it doesn’t work remove cookies and cache or use 1.1.1.1. And if you want to change hosting provider, remove the domain from your account and deactivate it, change the nameservers to the other hosting provider and wait 24 hours.
Remove the domain from the Addon Domains section on the Control Panel, then go to the account you want to delete on the Client Area, then click on “EDIT ACCOUNT”, scroll down and click on “DEACTIVATE ACCOUNT”. You should see “DEACTIVATE ACCOUNT” after some time from the hour you removed the domain.