Method 1
2. Select Applications > Manage Application
3. Find " Google Apps "
4. Select " Clear data " button
5. Now in the notifications , you will see a new notification
6. Select " Your account must be updated "
7. Add new Google account information
8. Then reboot your android device
Method 2
2. Open Root Explorer
3 Explore to / data / system
4. Find the file " accounts.db "
5. Delete that file ( accounts.db)
6. Reboot your Android device
7. Now you can register new Gmail account
Enjoy