ble_gap_unpair() function
Unpairs a device with the specified address. The keys related to that peer device are removed from storage and peer address is removed from the resolve list from the controller. If a peer is connected, the connection is terminated.
Arguments
peer_addr
Address of the device to be unpaired
Return value
0 on success; A BLE host HCI return code if the controller rejected the request; A BLE host core return code on unexpected error.