“You cannot change the store front information for your account at this time.”

If necessary, contact iTunes Support for assistance. See the Apple Support articles below for contact information.   

iTunes Support – world wide   -

Apple Support schedule phone call     -

Billings and Subscriptions   -

If necessary, use Twitter or Messages.

Apple on Twitter

Messages chat with Apple

Very likely there is a balance in your account in your original country. You must zero that amount before you may change the country. Purchase something costing that much or more.