Before selling your old iPhone,the first thing you need to do is erasing all contacts on iPhone permanently,in order to avoiding your important information be stolen.
Did you ever wonder how to quickly delete contacts from your iPhone? Then you probably found out, that by default there is no quick way to wipe your iPhone address book. You only can delete iPhone contacts one by one in following these steps:
1.Open the address book app on your iPhone
2.Select a contact that you want to delete
3.Tap on "Edit"
4.Scroll down to the end of the contact
6.Confirm your choice in tapping once again "Delete"
7.Repeat this for all the contacts that you want to remove from your iPhone
If you want to delete several iPhone contacts at once, you will have to use a 3rd party app like CopyTrans Contacts, "Cleanup: remove multiple contacts fast", "Delete Duplicates and Contacts - Easy Delete", or "ContactDel: delete multiple contacts with one touch".
The quickest and most convenient way to delete iPhone contacts is - in my opinion - the use of iPhone Contacts Eraser tool. The software allows you to select all contacts with one click and to save your contacts to the PC, before removing them from the iPhone.
Deleting iPhone Contacts Permanently with iPhone Data Eraser
To delete contacts from iPhone permanently,you need to use a professional iPhone data eraser application. To save your time to look for a suitable tool by trial and error, you can try my recommendation: iPhone Data Eraser (for Windows 8/7/XP/Vista) or iPhone Data Eraser for Mac, which is a quicker and easier contact erasing process on all iPhone models at once,you can erase contacts from iPhone 5s, iPhone 5, iPhone 4s, iPhone 4, iPhone 5c permanently. It not only delete data from iPhone without recoverable, but also rewrite with radom data in order to cover the erasing track. What’s more,this iOS Data Eraser also can help you erase contacts, text messages, videos, photos, account info, passwords and more from iPhone, iPad and iPod directly.Let’s teach you how to deleted iPhone contacts before selling it.
Please read this use guide about how to deleted contacts from iPhone permanently
PS: Normally you'll have to share the app on Facebook, Twitter etc. to get more free actions. I decided to purchase the app - that's why you don't see the counter button with the free actions left.