Can’t uninstall Simple Tags

Basically what the title says. A few weeks ago, I started having troubles with categories (which is fully detailed in this thread http://mu.wordpress.org/forums/topic/18313?replies=3, second post) and according to the tracing I made, it was related to this plugin. I uninstalled it, even deleted the files from the directory, but the plugin left a lot of its settings still active. In fact, it can be seen on Role Manager, even though it’s obviously not meant to be there.
I’m using WPMU 2.9.2, and even though I know this isn’t the forum for that, there isn’t a support section for this plugin on that board. It basically crashed my categories settings, and I’m not sure how to fix it beyond deleting the leftovers. These are the tables that appear after doing a global search on the database (using %simple%tags%):

http://img808.imageshack.us/img808/6342/comunicaswpmudb5411681h.jpg

How do I clean them up? If you need the full content of these fields just let me know, but this plugin affected greatly the categories and other related sections, which is a bad thing since I can’t do certain queries without fucking up the database.