Samsung HF4000 User Manual page 17

This function is available only on the Hands-Free profile. For more
information, see your phone's user manual.
DB deletion
When the hands-free car kit is paired with your phone, it automatically saves
information from the phone, such as the Bluetooth address or device type. With
the DB feature you can delete all saved information from your hands-free car kit.
1 Enter DB deletion mode.
In Pairing mode, simultaneously press and hold both the Volume buttons
for 4 seconds. You will hear "DB deletion mode."
2 Press the Volume down button. You will hear "Deletion completed."
If you don't press the Volume down button within 5 seconds, you will hear,
"Cancelled." And the hands-free car kit enter Pairing mode.