The "clear report" button belongs on the Report view somewhere.

Currently it is two windows away, buried in the Settings dialog.

Reports are auto cleaned to keep the size limited, the clear button option is just there in case someone wants a manual clean but it is not really required.

The clear button is more useful than that. Unlike previous versions, KIS 2009 does not have a report view that shows information only about the currently running scan. Instead, the view is cluttered with the history of all past events as well. Since history logging is no longer presented separately from information about the current task, it is useful to be able to clear information about irrelevant past tasks off of the screen when viewing information about the currently running task.

Also, in any case, clearing the reports is directly related to... reports. Therefore it should appear in the same place that you view reports. Period. A settings button on the report view that shows report-related settings makes sense for the same reason.

The one thing that would make this suggestion less useful is if, like pre-2009, there actually was a special details view for the currently running scan that was separate from the report logs of all previously completed tasks (then you'd have no compelling reason to want to delete the past reports conveniently). However, that is a separate feature request that should get its own thread.