If the uninstallation program does not complete successfully, it can leave some files that can prevent you from reinstalling into the original directory. If you are not planning to reinstall, you do not need to follow these procedures.
You can reinstall without a clean machine. However, such an installation creates a coexistence scenario that can prevent you from installing into the original directory.
Cleaning the machine means deleting everything from the previous installation, including log files that are left behind by the Uninstallation wizard or silent uninstallation procedure. Before you start the procedure, back up log files, if necessary. See Log files for the location of log files.
Follow the appropriate procedure for your platform to produce a clean machine.
Cleaning the system eliminates all evidence of a previously deleted installation.
After you have cleaned your system, go to Installing WebSphere ESB to select an installation procedure.