Well, there are two ways to clear analyzed data. One is through sql and the second is through sd interface.
If you want to delete them from the database server just run the query delete from itsm_analyzed_data
But the safer and more slow is to delete them through sd interface. To do that
Open Report Settings from the system panel on the administration console. At the tab "General" note what reports are not blocked and then block them.
Go to the next tab and note what items are checked. Check them all. Then go to the previous tab (General) and disable "Enable 'on Sabe' Refresh of analyzed data". Press the button "Refresh Analyzed Data..." and select "All Data". Press OK
Some hours later when it finishes, the analyzed data table should be empty.
Since, however, generally it is a good idea to have analyzed data enabled, after doing your job, unblock the reports you are interested, check the entities you are interested, check "Enable 'On Save'..." and regenerate analyzed data.