[nRF Connect SDK]How to accept new incoming connection and disconnect existing connection

Target nRF52832(nrf52dk_nrf52832)
SDK NCS v2.0.0

One of my customer expects such a scenario.
1) BLE accept first connection.
2) If BLE have another connection, BLE disconnect previous connection, so that BLE have one connection. (always have last connection)

I changed CONFIG_BT_MAX_CONN from 1 to 2.
But I'm having trouble with handling disconnect previous connection.

Do you have good idea?