Please confirm whether the API result is success or not. Once the API result is success, you can check the bond device count by API CyBle_GapGetBondedDevicesList. Please share your project to recreate the issue.
I would like to know where is the best place to remove the bonded information?
Is it at the start of another pairing?
Or, at which event, can I remove the bonded information?
To remove the bonding information, disconnect the connection and during the advertising we can remove the bonding information. Please refer Day015_Bonding Project in the GitHub for more information on storing and removing of the bonded data.