You can also use the move feature found within your site manager to move your siterubix subdomain to your dot com, when you are ready. It is a simple process.

You would need to wait up to 30 days (Kyle's recommendation) for 301 redirects to be completed and for the search engines. After of which you MAY delete the subdomain however you could keep it for longer if hosting space is not an issue or for testing purposes such as themes, plugins, scripts, coding etc

You can check Kyles training tutorial below Move On Over, My Brand Has Arrived

If you want to change the URL of a siterubix subdomain or dot com domain, you can delete and start again, however I'd save my work in site content.

If title and tagline (Just another WordPress site), settings > general edit and save changes.

To delete a siterubix subdomain | or dot com, click details on subdomain in question in site manager, onward next page scroll all the way to the bottom and click delete.

https://my.wealthyaffiliate.com/websites

Then you may go to Site Builder

https://my.wealthyaffiliate.com/websites/build

Choose a free domain, a domain you own or register new, enter credentials and follow procedure.

if both are hosted here then you can use the move button under websites>>siterubix to move the contents of a siterubix to a domain or domain to domain easily.
but you can't jsut change hte name of a website - each one is individual and logged on a register ...otherwise there would be chaos...
so you can change the dispaly name on the site by going to settings...
but the url ..you will need a new domain...and move the contents across to it...