I want to uninstall and completely remove QGIS installation from my computer(windows vista). I have uninstalled it and when i try to reinstall it says it is already installed on the system.
You can make sure all folders in your hard drive and your
.qgis2 folder (
C:/Users/You/.qgis2) are deleted. You could also delete the Registry entries for QGIS by running the regedit program and searching for QGIS:
Hopefully when you restart your computer, you will be able to reinstall QGIS again.
Hope this helps!