you can also apply this registry patch for deleting the search history:


copy and paste and save as XLXCLR.REG

----- cut here ------vvv

REGEDIT4

[HKEY_CURRENT_USER\Software\xolox]
"search history"=""

----- cut here -----^^^

then double click it to delete search history (make sure xolox isn't running, exit via the systray icon)