Small script to unsource variables from a script or file. See http://nextrevision.github.io/2015/unsourcing-vars-files-in-bash/

unsource.sh

#!/bin/bash -e

if [ -z "$1" ]; then
  echo "usage: unsource.sh vars.env"
elif [ ! -f "$1" ]; then
  echo "No such file: ${1}"
else
  __start_env=$(mktemp -t unsource.XXXXXX)
  __end_env=$(mktemp -t unsource.XXXXXX)

  env -i bash -e -c "declare -f | egrep '^\w' | cut -d' ' -f1 > ${__start_env}; \
    export | cut -d' ' -f3 | cut -d'=' -f1 >> ${__start_env}; \
    set -a; \
    $(export | cut -d' ' -f3- | grep '=' | tr '\n' ' ') source $1; \
    declare -f | egrep '^declare' | cut -d' ' -f3 | cut -d'=' -f1 > ${__end_env}; \
    export | cut -d' ' -f3 | cut -d'=' -f1 >> ${__end_env}"

  for __target in $(diff ${__start_env} ${__end_env} | egrep '^>' | cut -d' ' -f2); do
    unset ${__target}
    echo "Cleared: ${__target}"
  done

  rm ${__start_env} ${__end_env}

  unset __target
  unset __start_env
  unset __end_env
fi

Cool. What if unsource without parameters just reset you back to a clean environment?
Also, any reason why I wouldn't just copy or symlink unsource.sh into /usr/local/bin and call directly?