I am writing this from my personal experience. Due to the fact that I have used Android and BlackBerry in the past, I have sync basically all my contacts on my emails and when I got myself an iPhone 4S, I told myself that I am going to sync everything I have to iCloud. However, having multiple emails for both work and play lead to a very common issue: Duplicate contacts! It was really hard to clear one by and I finally managed to merge everything into one. To my dismay, another issue came up which is, how could I delete all my contacts on my iPhone now before I can sync with the almighty iCloud? After multiple testing and try-an-error, I managed to get them working as what I wished for and I am going to share with all of you.

Method 1
If you have save all your contacts in your emails, all you have to do is to use the import/export button to get them on board to another email and get all your contacts into one. With this, you can deleting the rest of the contacts just to make sure that you have the right one in place.

1. Import/export all details to one main email
2. Delete all the duplicate ones
3. Sync with iPhone

Method 2 (easiest way)
Do you want to clear all your iPhone contacts in just less than 5 minutes? Well you can do it without iTunes or iCloud help and this is definitely the fastest way around. Trust me and here's how:

1. Make sure you keep the backup in your computer just in case.
2. Turn on Airplane mode and even turn off Cellular Data.
3. Now head to Setting > Mails & Contacts > Select Mail Exchange
4. You can use these as your login and password (a fake account works as well):

Email: aaa.gmail.com
Login: aaa
Password: aaabbb


5. Now, it will ask you for the server address and you can type this:

m.google.com

6. The system will run and an error will pop up telling you it can't be done. Press Next or Accept to ignore.
7. Now, it will ask you to Save or Exit and select Save.
8. Finally, a pop up message will be asking you if you want to transfer/sync your contact from the Exchange account.
9. Select Yes and another pop up will ask you if you would want to delete all the contacts in your iPhone right now.
10. Another Yes and you have completed everything!
11. Of course, now you can your your data on again and delete off the Exchange account.

Now, enjoy!

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