qmake for beta2 is still auto detected in Qt Creator after uninstallation

For those who have installed the beta2 version of Qt5, qmake from beta2 will still be shown in the auto-detected qmake in Qt Creator.

Steps:
1 - Install beta2
2 - Open Qt Creator->Preferences->Build and Run
3 - qmake from beta 2 is auto-detected
4 - uninstall beta2
5 - install RC1 package (i.e. 351)
6 - qmake from rc1 is auto-detected as expected

problem => qmake from beta 2 is still auto-detected while it does not exist anymore.

This can be worked around by moving %APPDATA%\QtProject to %APPDATA%\QtProject_old (QTBUG-28222)

This could be listed as a known issue until this is fixed.