Is this just a matter of deleting:
1) the \webinator directory structure
2) the DB, if not in the webinator structure
3) the \texis*.dll in WINNT\System32
4) any texis files in the IIS scripts directory
I hate to pick nits, but your subject says your question is about webinator 2.5, yet you posted it to the webinator 1,2.1 group instead of the webinator 2.5 group.
Sorry about that - I only subscribed to this board yesterday, and didn't realize that the board messages were split up by version. I think the reason I hit that old v. 1/2.1 one is that I had searched on "uninstall" and found a couple of messages that must have been from that old board, so when I selected to post it defaulted to that board.