If you try to delete some apk files from /system/app, you will get an "Read-only file system" error. This is why /system is mounted as read-only.
To be allowed to delete data from /system/app, we need to remount it as read-write. How can i do that? Well it is very simple, we only need a Terminal application and execute a few commands.
- Open our Terminal application and exec the command "su" (super user, root) to request root privileges.
- Exec the remount command: "mount -rw -o remount /system".
- Then we can delete the desired files with the command: "rm /system/app/file_name". Proceed with caution! And don't delete files if you don't know what are you deleting!
- Reboot. At the next start /system will be read-only as it should be.
This is very useful for removing app's that are included with our rom's by partners or manufacturers, and can't be uninstalled with the app manager.