End-users often push the Exit button during an installation, and start over again. So it is essential to handle cancellation of installations well and thoroughly, especially when you also install third party software.
LizaJet installer rolls back the full installation when a user pushes the Exit button, during the installation LizaJet Installer stores all atomic actions in a log file. When a file is deleted or updated When the user presses Exit during the installation process, the log file is read backward, and all actions are reversedit is copied to an undo folder. 

LizaJet Installer also rolls back a part of the installation when the user presses the Previous button in the Installation Dialog.

LizaJet Installer has a comprehensive set of inbuilt functions, each function contains the installation action as well as the reverse action; for instance the function for stopping a service contains a reverse action for starting the same service. 

For special functions you add to the installation LizaJet Installer provides an extra undo handler, so you can determine exactly what must be done if the user presses Cancel after your special functions was executed.