It’s easy to remove one contact at a time from your iPhone’s contact list; however if you want to wipe all of them in one go, the process becomes a tad difficult.
To delete just one contact from your Apple device, it’s enough to access your contact list, select the contact, press edit and choose Delete Contact from the lower right part of the screen.
For full contact list wipe there are various free tools in AppStore – however for this tutorial I chose a paid app since it packs a number of useful tools under a single interface. Using Cleaner Pro ($2.99 on iTunes) you can wipe your entire contact list, remove duplicate contacts, merge similar contacts and, last but not least, regularly backup your contacts and forward a copy to your email address. Cleaner Pro is especially useful if you are not fond of backing up your data in iCloud, but can be used in any circumstances.
After installing Cleaner Pro you will have to allow the app to access your contact list. On top of the main screen select All Contacts. Touch the pencil in the upper right corner to enter contact editing mode and click the top checkmark to select all your contacts. To finish, touch the recycle bin in the lower right corner and confirm your selection.
If your purpose is to remove duplicate contacts, select Duplicate Contacts from the main screen. The app will automatically display a list of duplicate contacts found in your iPhone. Check the list and unselect any mis-detected elements then press Merge.
It is highly recommended to do a full backup of your contact list before wiping or merging contacts – Cleaner Pro offers various options to do so. Press Backups then tap Backup Now and choose to have them delivered by e-mail or uploaded directly to Dropbox.