For most of the linux users history of commands in shell is a grace. Up/Down arrow
keys help them to find the previously executed commands.But for someothers it may
be a curse.There are situations in which you don’t need to reveal previously used
commands in linux terminal, especially when your system is being used by others.

Linux provides an easy method for removing the history of used commands. Keep it
safe and simple by editing the .bashrc. It is hidden by default in the home folder.

1. Open .bashrc in shell by nano .bashrc
2. Move to the line where
HISTSIZE=10
HISTFILESIZE=200
is written.
3. Edit the numbers to look like
HISTSIZE=0
HISTFILESIZE=0
4. Now you can logout and check the changes made
by pressing the Up/Down arrow keys.