Country/Region greyd out when creating Tax Region

Greating!

I want to create a Tax Region for a country different from USA but the country/region field is grayed out. Does Someone has any ideas on how can I change this field?

0753.Error-TaxRegions-PaisRegion.png

Any suggestion will be appreciated.

*Greetings

looked at the code, only USA is allowed. You cannot change it.