Hi,
I believe the command would be:
set ethernet-switching-options voip interface ge-2/0/15.0 vlan "vlan-name"
For vlan member, the vlan name should be specified instead of the vlan-id [compared to Cisco].
Could you check the vlans in operational mode and look for vlan name for vlan-id 80:
show vlans
To zeroize config on a port, you can do "delete interfaces x/x/x".
Cheers,
Ashvin