Suppose you registered ONT or it registered itself on BDCOM OLT as I described in this article – Configuring BDCOM P3310 EPON
Now to remove it from the configuration, connect to OLT and go into the configuration mode:
enable config
Let’s look at the current configuration and find the MAC address of the ONT you want to delete:
show running-config
Choose the interface (port) on which ONT is registered:
interface EPON0/1
And delete ONT, for example with mac address e067.b336.88e8:
no epon bind-onu mac e067.b336.88e8
Done.