CHANGING APPLE ID/EDIT ACCOUNT INFORMATION/CHANGE ITUNES COUNTRY
Tap Settings / iTunes & App Stores, then tap the Apple ID signed in. Sign out of the current Apple ID account and then sign in with another account or create a new Apple ID http://support.apple.com/kb/HT2731?viewlocale=en_US
To edit account information tap Settings / iTunes & App Stores / Apple ID: / View Apple ID
To change your iTunes Store country, sign in to the account for the iTunes Store region you would like to use, tap Settings/iTunes & App Store/Apple ID/View Apple ID/Country/Region
Read this article for information http://support.apple.com/kb/HT1311
First of all, content bought using one Apple cannot be merged or transferred to another Apple ID.
Apps, books and music are tied to that Apple ID.
Manage Apple ID:
1. Transfer data from old iPhone to computer:
2. Make a backup
3. New iPhone restore from that backup