Problems with changing the default country in Google Play Store
unfortunately you can't do it in google play.but can login to your google account, and there you click on edit next to your email id and here you can see the option to edit information in the country field. Now you can change your country whatever you want.
but if this won't help you and want to access the playstore apps that have a country restriction, you can use apps like Hideman hideman VPN playstore link  to access play store apps via their servers at USA and you can actually download them.