Adding or removing the "www" prefix from your domain is done in the Templ panel. Nothing needs to be changed in WP Admin, changing the address there will cause problems. Once you have made the changes as described below, the WP Admin "Site URL" and "Home URL" are updated automatically.
How to add or remove www from your domain
Step 1: Add your domain with the www prefix in our panel.
If you want to remove www from your domain name then you add the domain without www.
Step 2: Change to preferred domain in the Templ panel.
That's it. You have now updated your domain name. Search-replace from the old address to the new address will happen automatically.