How do I change the URL/Domain Name?

I want to change the Domain Name to exclude the .myspreadshop and was wondering if that is possible, and how I would ago about doing so?

Basically, I want it to read: instead of:

Hi, unfortunately you can’t change the URL of the Spreadshop regarding the You can only change the shop name here. If you want your own domain you can buy it with a web host of your choice and then embed your shop to this website.