In the advanced option of the cleaner page which are safe to delete of those listed? Or is it actually necessary? I delete the prefech data but am wondering about the rest, particularly hotfix uninstallers. Frankly, I don't have a clue what they are
If you delete the hotfix uninstallers, you will not be able to uninstall the hotfixes installed on your PC - so make sure they are working OK before you uninstall!