Clearing out your bash history can be quite a hassle as it keeps a copy in the memory that will be flushed at the moment you log out. There is a workaround:

cat /dev/null > ~/.bash_history && history -c && exit

After this command the history is wiped.
I use this when creating binary copies of the filesystem when I do not want to include any history (Create bitwise copy of EMMC/SD/HDD/SDD over the network (backup using ssh pipe)).

Source: https://askubuntu.com/a/192001