Mandatory information about my setup:

Have I searched the tickets before posting? yes
Have I searched the forum before posting? yes
Have I read the documentation before posting (which pages?)? yes
Joomla! version: (2.5.16)
PHP version: (unknown)
MySQL version: (unknown)
Matukio version: (3.0.6)
Direct link to the page that shows the issue: (unknown)


Description of my issue:
I've deleted a few categories from the backend of Matukio 3.0.6 but they still show up in the drop down menu on the create event form. How can I delete them permanently from the drop-down menu?