[Windows Central Question]

want to send a company phone from an x employee to a new hire and want to clean the contact list out first

[-8-]

The best thing you could do is to reset the phone to remove not only the contact list, but also old messages, browser history, apps, etc. Essentially you throw out the old Microsoft account so you can start fresh with a new one. To do this go to Settings, Info and tap factory settings.

But if you only want to delete the contacts:
1. Go to the People app
2. Tap More (...) and tap select contacts
3. Tap More again and tap select all contacts
4. Tap delete