Root, but "file cannot be deleted" I've rooted my worlds-lowest-end-tablet the Azpen A727 successfully a while back.  In my quest to recover as much of its tiny memory as possible, I came across a folder called /system/preinstall which has several .apks in it, for software that came with the tablet, that I don't want, and have uninstalled.

When I try to delete them using ES File Explorer, the app successfully gains root, but I get a message "[filename].apk cannot be deleted".

Is there a power greater than root?
Indeed there is: "root that knows what it's doing" ;)


you gain no usable free space from deleting stuff below /system, as that's the OS's domain and not used to place user content / user apps
As the user is not supposed to change stuff here (and neither is the OS while running in "normal mode"), /system is mounted read-only – which means you cannot write (nor delete) in this mode. If for some reason (which you should be sure of, know about possible side-effects, and have taken appropriate pre-cautions) you need to write there, you'll first have to re-mount it in read-write mode.