Sometimes it’s easier to reset all the data you’ve been playing around within your account than to delete, expire or archive everything one-by-one.
Wiping all data in your account
Go to your Settings in the bottom left corner of your screen
Click Clear all data in the Data usage panel
1) Contacts will be deleted, but Users will remain in your account. Their associated contacts will get recreated.
2) Be careful. Clearing the data from your account cannot be undone!