The ►UC◄ label is part of the voicemail system. This label is required for your voicemail messages to sync to your Bmail Inbox. If you delete this label, you will not receive voicemail messages in your email, but your messages will still be on your telephone.
This label can be found at the bottom of the label list under More.
This label can also be found in Settings, Labels. It will be the top item in the label list.
If you delete this label, copy ►UC◄ and paste it as the name of a new label. You must copy this exactly as it appears.