The program injected data into
~/Library/Application Support/SyncServices/Local/TFSM by calling code to add their sync schema to Mobile Me's local sync database. You want that program to call unregisterSchemaWithName before you delete it so that data is deleted out of MobileMe.
The Local SyncServices folder governs iOS device sync as well as MobileMe sync - so use care to keep those devices away from your mac if you with to proceed in a manual clean up.
It's a really bad idea to simply delete files out of that folder if you are not prepared to have sync break in very ugly ways (I have seen people end up with 10 copies of each contact, calendar item and bookmark by moving / disturbing things in SyncServices) If you have a great backup and don't mind erasing everything from MobileMe and re-syncing from a computer - have at hacking the folder. There's no better way to know how things work by breaking them. Apple has an eloquent warning that starts... "As if it were a swarm of bees, you should stay away from the SyncServices folder."
You can see what a sync schema looks like by reading the database of files on your mac in the terminal
locate syncschema. These files and folders define how data gets injected into the sync database with the registerSchemaWithBundlePath call and may have clues on cleanup scripts or steps.
Your best bet is to contact the vendor and ask them what steps to take to undo their changes. Apple has been changing the internals of how mobile me works lately, so there are no for certain steps that work across all versions of 10.6.x and your specific data in MobileMe. Since MobileMe is a paid service, you might also get general guidance from Apple Support in cleaning up the preference pane even though it's a third party data addition. They did add hooks and intend to let other apps to the sync party so they might reasonably help you clean up after the fun is over.