"Price is locked and cannot be edited" - how to unlock this or any other field

So to cut it short, just write this in your code, probably devel/php, change the filed name and you will have unlock a filed (probably commerce_price field).

$field_name = 'field_name';
$field = field_read_field($field_name);
$field['locked'] = 0; // 0: unlock; 1: lock.
field_update_field($field);

After you do what you need to do, you should put it back to lock.