Bash is a Unix shell written by Brian Fox for the GNU Project as a free software replacement for the Bourne shell (sh). Released in 1989, it has been distributed widely as the shell for the GNU operating system and as a default shell onLinux and Mac OS X.
how stuff work: normally after typing commands bash will keep the history in ~/.bash_history file up on log out
you can login and edit / remove .bash_history file in your home folder will do the trick
macbook-pro-2:~ ajay$ vim .bash_history
it helps even if you only need to delete last 10 commands you run..