You can't change your actual username, but you can change you handle in games by going to diplomacy, clicking on your country, clicking on your name, and editing it. Hope this helps.

You are granted 1 name change for your account. This can be done under the account setting (bottom left corner of main menu, select the more option to find this location). If you have not changed your name yet, there will be a place to do it, if you have already changed it, there is no option.

Another thing I've seen NWO say in the Bytro CoW Discord is that if you have had your current name for 6+ months, you can submit a support ticket requesting a name change. Just provide 3 names you would like to have.

The above worked when changing my name from 2 to 6. Simply ask in support, I think the other option does it??? (DO NOT QUOTE ME ON THAT!!!)