root access - Where are the lollipop OTA system upgrade files stored?

Android devices automatically download OTA system update files and store them on your device until you install them. Then you get a notification that the file has been downloaded. I do not want to update using this OTA file. I just would like to delete the OTA file but cannot find where it is stored. In the past they were stored in the /cache directory, but with lollipop that no longer seems to be the case.