For iPhone 4 feature supported delete contacts one by one. Click on the app "Contacts", located on the main screen that appears after pressing unlock the phone.
You will see a list available in the contacts menu. Select the position you want to delete by clicking on it with your finger. Click on the "Edit" button in the upper right corner that appears contact.
Scroll the specified data down until, until you see the "delete" button to Confirm the operation by clicking "Delete" again. Now the contact will be erased from the notebook and cannot be restored by means of phone.
You can also remove all contacts that are in the list. For this you will need to connect your phone to computer and sync your data with iTunes. Connect the phone using the USB cable that came in one package with the camera when purchased.
You will see the iTunes window. Click on the image of your device in the upper right corner and wait for the list of categories available to control your smartphone. Click on the button "Information" in the top bar of the program.
Check the box next to "Sync contacts" and select "All contacts". In the section "Advanced", check the checkbox next to "Contacts". Click "Apply" in the lower right corner of the program.
In the dialog that appears, click on the "Replace information". All contacts will be deleted from the phone book of the device. Delete contacts iPhone 4 completed.
If your phone is jailbreak, you can use the app Erase Contacts, which is part of the repository Cydia. Enter the name of the program in the search box and type the app name. Install the application and run it after the installation procedure. Immediately after clicking on the application shortcut all contacts will be permanently deleted.