To remove hardware or software from a computer system. Uninstalling hardware requires removing the driver from the operating system. Uninstalling software requires removing all the files that were copied to the hard disk during installation as well as deleting Registry entries for Windows applications. Earlier PC uninstallers restored the AUTOEXEC.BAT, CONFIG.SYS, WIN.INI and SYSTEM.INI files if they were modified during installation.

Most applications come with their own uninstall utility, which is part of the program that installed the software in the first place. When installing, the install program records all changes made to the computer so they can be reversed when uninstalling. See install program.