Removing a reminder that seems to be stuck

We have RT-3.6.0 on a SuSE SLES 9 server here and somehow I have an RT
Reminder that will simply not go away. It shows up in the Reminder Module
on the At a Glance Page. If I click on it and go to the ticket it is not
shown and therefor cannot be “checked” to be completed. I’ve tried closing
the ticket but that didn’t do it either.

What would be the cleanest way to remove this reminder (via the Web or the
Server, I’m the admin)?