Change Hostname URL – Please Help Me!

Hi guys!

I can’t find any reference to my problem, so I hope someone will be kind and help me out on here.

My blog has a .com domain but there is an alternative URL to my blog too; https://www.myblog.HOSTNAME.com
I would like to change the settings in WordPress so that my only URL is https://www.myblog.com.

I was wondering if it could be done in

dashboard–>general settings–>

WordPress address (URL) / Blog address (URL)?

Both fields says: https://www.myblog.HOSTNAME.com
Could the change be made there?

I really appreciate any help, Thank you for reading this.

Linda