Status 403 (Forbidden)

A while ago, I uploaded my web pages and it worked fine. Then a few days ago, I tried opening it again and it failed to receive data from the database with the error:

Forbidden

You don't have permission to access /absensi/index.php/Ajax/get_contactTypes
on this server.

"status":403,"statusText":"Forbidden"}

I googled the error, and found most say that it's because of the Apache, yet I didn't do anything to it.
The only change I did was adding a new domain, so most likely it's the cause. So I tried to delete the domain, but then it said

"ERROR! You do not have permissions to delete domains, please contact system admin."

I searched for the solution and found a topic "Delete Domain" on this site in which the admin said

Just log in to CWP.admin and check who is owner. And you can delete it from CWP.admin.

But I don't know how to log in to CWP.admin.

So, does it have anything to do with the Apache, or is it because of the new domain I added, or both? If it's because of the Apache, what should I do? If it's because of the domain, how do I log in to CWP.admin and delete it?

Replies will be very much appreciated. Thank you.

you can login to by using the root user and fix the permission for the account

Thank you very much for the reply. I'm using a free hosting which uses Centos-Web Panel. Turns out I don't have root user account, so I contacted the admin and my domain was successfully deleted. Sadly, the "Forbidden" error still remains.