This could also have been a .bat file, there is no specific reason that I made it into an AutoIT script. So, now you know that ;)

ResetOSTFile.au3

; Kill Outlook
RunWait(@ComSpec & " /c taskkill /f /im outlook.exe")
; zZz
Sleep(1000)
; Delete OST file
RunWait(@ComSpec & " /c del %LOCALAPPDATA%\Microsoft\Outlook\*.ost")
; zZz
Sleep(1000)
; Start Outlook
RunWait(@ComSpec & " /c start outlook")