Change existing contacts from 'phone' to 'gmail'
You need to export your phone contacts in to vcf format and then again import it into Google contacts.

Steps in Android 4.2:


contacts -> settings > Import/Export -> Export to storage.
contacts -> settings > Import/Export -> Import from storage. - This will ask you to select your Google account to save.


Edit/Delete or remove duplicates in http://contacts.google.com. Thats easy.