This is probably more than you'll need to do, but this is a complete manual uninstall of VectorWorks on a PC:
1) Click and drag your VectorWorks folder (Default location: C > Program Files > VectorWorks) to the recycle bin. Empty the recycle bin.
2) Click Start > Run and in the dialogue box that pops up, type ?RegEdit?
3) On the left hand side of the window that pops up, ?Registry Editor? you will see a few small icons that look like folders with + or ? signs next to them, click all the "?" signs except the one next to ?My Computer?, you should see one folder labeled: ?HKEY_CURRENT_USER?
4) Expand this folder by clicking the "+" sign to the left of it. Inside you will see a ?Software? folder, expand it as well.
5) Right click on the ?Nemetschek? folder and select Delete. Do the same with the ?VectorWorks? folder.
6) Repeat these steps for the folder ?HKEY_LOCAL_MACHINE? as well.