Uninstall system app failed using 'adb shell pm uninstall' I attempted to force uninstall in ADB, but failed:

$ adb shell pm uninstall -k org.openintents.filemanager
$ adb shell pm list packages -f | grep -i manager
package:/system/app/FileManager.apk=org.openintents.filemanager


What went wrong here? What can I do?

I used the internal application manager and there isn't an option to delete it.
Well, since the FileManager.apk package resides in a /system/app/ directory it is a system app. So the general way to remove it is:

adb shell
su
mount -o rw,remount /system
rm -rf /system/app/FileManager.apk
rm -rf /data/data/org.openintents.filemanager
mount -o ro,remount /system
exit
exit