To provide feedback on your Firefox experience to the development team, select Tell us what you thought of Firefox.If you select this option, Firefox will not preserve your bookmarks, saved passwords, and other data if it is installed again. If you want to remove your Firefox user data and settings, put a check mark in the box that says Remove my Firefox personal data.
If the Uninstall Wizard does not run, you can start it manually, by running C:\Program Files\Mozilla Firefox\uninstall\helper.exe.