You can create a new dropdownlist with your own values like that:

VIEW:

 <option value="">Select country...</option>
       <t t-foreach="countries or []" t-as="country">
       <option t-att-value="country.id" t-att-selected="country.id == account.country_id.id"><t t-esc="country.name"/></option>                          
       </t>

CONTROLLER:

countries = http.request.env['res.country']

values = {
                'countries': countries.search([]),
         }
         return http.request.render('eq_website_customerportal.accountDetail', values)