There are some contacts on my phone which are stored in the Google Contacts. However when I try to edit these contacts and move them to the "Device" I cannot do so. Is there a way that I can move the phone number in the "Contacts" app to the device? If yes can you please let me know how to do it?
IF your contacts are stored in Google Contacts. They will automatically Sync with the contacts application on Phone.
If you are talking about 'Backup' or 'Exporting' contacts
Contacts > Settings > Export.
It will be saved in .vcf format