Use RevoUnistaller, do a full clean which will remove all directories and registry entries.
Bitcoin-Qt stores NOTHING in the registry. Windows on the other hand may store some information of what was last run/installed though.
You're right, it doesn't apart from some URL handling rules.
![](https://ip.bitcointalk.org/?u=https%3A%2F%2Fi.imgur.com%2F3Xfs1y8.png&t=662&c=Fedftap2HfHY5w)
Was just giving the OP another option if he wanted to remove all existing traces of it. IE, a fresh clean install.