The Debug -> Log files tab is only displayed when logging of debug information into log files is enabled for at least one type of debug. This can be achieved either by adjusting certain settings or by adding certain keys into the appSettings section of your web.config file. For more information on these settings and keys, please refer to the Site Manager -> Settings -> System -> Debug page.
This tab provides an overview of all log files stored in the ~\App_Data\ folder. By clicking the Delete () button, you can delete the respective file from the App_Data folder.
For more information about debugging in Kentico CMS, please refer to Developer's Guide -> Development -> Debugging and system information.