how to make BLE devices to ask for authentication before connecting to IOS apps or android apps

Hi,
I am using RTBTM01 BLE module, 

am not able avoid connecting ios app without pairing. my ble device automatically connects to both ios/android apps.

*) How to connect my BLE peripheral with ios app with pairing request only.

in our case it automatically connects with BLE peripheral without pairing.
our BLE's firmware already contains some default services, if i want to make encrypt
those serivices or characteristic in that services what are all the changes need to to be
done in app written on top of BLE stack.
i am using the example app given for Renesas SK board(project:an-r12an0056eu0100-synergy-ble-rl78-g1d)

*)
How to set permission to those characteristics to avoid connecting and advertising without pairing.

i have reffered some links also,

https://stackoverflow.com/questions/43567569/how-to-ask-for-authentication-before-connect-to-devices-using-bluetooth

https://e2e.ti.com/support/wireless_connectivity/bluetooth_low_energy/f/538/t/226814

*) some of them are saying to return error codes

if peripheral devices need pairing, peripheral should respond "Insufficient Authorization" or
"Insufficient Authentication" error code

if this is need to be done, how to do or which function should i use for returing above error?

*) otherwise please suggest me if there is any other way to avoid BLE connection without authentication?

Thank You