Looks like an inter-application messaging daemon. If you don’t know why it’s there and what apps are using it, then assuming your own account is an administrator, or. you can log in as one, then do so and delete that account. If something breaks in one of your apps as a result, at least you can explicitly address the re-establishment of the configuration.
Take a look at /System/Library/LaunchDaemons/ and see if there are any related components. (Also look in /System/Library/LaunchAgents/). If so, rename the component(s) – put a dummy extension on the end of them, for example – and reboot. See if the user still appears on startup.