According to the very limited information provided by Verizon: https://www.verizon.com/support/consumer/internet/fios/network-extender/wcb6200q-faqs
my verizon-installed FIOS extender should replicate the network names from my router (see below). I have followed the instruction of removing the power for 5+ minutes and the old SSIDs are still there. I've been on hold for 26 minutes so far waiting for Verizon support (and the chat function is "busy" right now). So, can any of you do Verizon's job on this and offer a suggestion to get my router SSIDs replicating on my extender? Thank you!
My Fios Network Extender is not replicating the Network name (SSIDs) from my router, what should I do?
You need to reboot the device by removing and reinserting the power cable of your Fios Network Extender. Within 5 minutes of the reboot, the Wi-Fi Name(s) should be configured on your Fios Network Extender.