How to delete a system android app?

Yesterday I was need remove some programs from my android. The app was in system so the originla methods doesn' help. As I use Ubuntu it's very comfortable work from console. Last time I used this method:



Connect phone with USB cabel and open terminal. Type
adb devices

The serial number of device should appear.
Then I perform this command:

mount -o remount,rw -t ext4 /dev/block/mmcblk0p1 /system

It should mount system folder. Then I set up 777 permissions of system folder.

chmod 0777 /system/app/

This command can be performaed only by root. So as usually I use command sudo su to get permissions.

Then simple command how to remove file:

rm system/app/Superuser.apk

Superuser.apk - that was app to remove. Please do not remove apps you don't know. It can be important for android system. But it you want of course you can. We live in a free world.

After removing all required apps I restore rights on system:

chmod 0755 /system

and unmount system folder:

mount -o remount,ro -t ext4 /dev/block/mmcblk0p1 /system

This is an ideal variant without any errors. In practice there are a lot.
For example, abd command usually writes me that it can be found:

kate@Mob_:~$ adb
The program 'adb' is currently not installed. You can install it by typing:
sudo apt-get install android-tools-adb

I really don't know why it happens as I has writen it in the system path. So I need go to the folder of android-sdk and launch it with point:
cd ~/android-sdk-linux/platform-tools/ and ./adb. For example: ./adb devices

The second my error was wrong permissions on folder. At first time I set up 644 on system/ (I was watching some serial :-D ) and it was hell to restore it back. But it is the other story.