https://unix.stackexchange.com/questions/544373/how-to-clear

HISTFILE=${ZDOTDIR:-~}/.zsh_history
HISTSIZE=20
SAVEHIST=$HISTSIZE
setopt extended_glob
function erase_history { local HISTSIZE=0; }
function zshaddhistory_erase_history {
  [[ $1 != [[:space:]]#erase_history[[:space:]]# ]]
}
zshaddhistory_functions+=(zshaddhistory_erase_history)