How to Remove and Change Gmail Account on Android Market without doing Factory Reset from your Android Phone

When  tried to remove (settings->accounts & sync) the gmail account that was used during the initial phone setup, it erase almost anything on your phone, like contacts, photos, messages etc, and prompted this message ->

Remove account
This account is required by some applications. You can only delete it by resetting the phone to factory defaults.

Doing factory reset to change Gmail account on android market is a hard way. Via resetting your phone all phone contents will be lost, like messages, contacts, photos.. etc. To do a factory reset of your phone will make you set it up again from scratch. But don't worry guys there are some simple ways to remove or change Gmail account on Android Market without doing factory reset from your phone.


Method 1

1. In menu > go to settings
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 (ROOT access needed)

1. Download the application Root Explorer from Google Play (Android Market) 
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


References:
http://vybrend.blogspot.com/2012/08/how-to-remove-or-change-gmail-account.html
http://droidtricks.blogspot.com/2011/07/how-to-remove-and-change-gmail-account.html
http://forum.xda-developers.com/showthread.php?p=18618452