Messages app showing unread number after deleted message. Can remove/reset? [duplicate]
Solution 1:
Two options:
- Close Messages.app, then in the Terminal
killall Dock. This worked for me. - Identify the message that Messages believes is unread (hover over icon in Dock) and delete it on your iDevice(s).
From here: http://forums.macrumors.com/threads/unread-messages-badge-on-mbp-is-stuck.1806575/
Also, this seems to be a duplicate of Why does Messages on OSX always show unread messages?