5. Uninstall all applications that are no longer needed. When applications and games are installed to a Windows PC, some files are written in the Windows directory structure and dozens (or more) changes are made to the Windows Registry file. Most of these changes are not readily apparent to the user, so proper removal requires uninstalling the application through the Control Panel's "Add or Remove Program" or "Programs and Features" icon. There are 3rd party applications that can assist removing applications that do not have uninstall routines - or do not fully remove themselves. Revo Uninstaller Pro and CCleaner are two such popular uninstall applications.
If the program is not listed in the Control Panel use the "uninstall" command provided by the application.
Simply deleting the entire application directory is not the same as uninstalling, as all the files written to the Windows directory and changes to the Windows Registry file will remain and may be reloaded when the system is rebooted.
Make sure that you do not uninstall any programs that are required by others. e.g. iTunes will not work if Quicktime is uninstalled, and many programs rely on other Microsoft programs.
Follow here for tip 6-
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