How to temporarily disable history in zsh like bash at the end of the session?

In bash if we run unset HISTFILE at the end of the session then it does not save the commands that ran during that session.

But in zsh, after we run unset HISTFILE or fc -p, it stops recording commands to history for that session.

unset HISTFILE...secret commands...exit

1. it stores unset HISTFILE or fc -p in .zsh_history
2. it should be executed before any session, not at the end