Hi, Lane!
Jimbuna said it: Use the Add/Remove Programs function, then go to Program Files. You might still have and Ubisoft folder there. If there are other games in the Ubi folder, drag and delete SH3. If not, dump the whole Ubi folder. Then you need to go to the My Documents folder and delete the SH3 folder there.
Hows
Das Boot, by the way?