Hello,

What I usually do is to use the unset command. All that you need to do is to run the following:

unset API_KEY

If you are writing a script, for example, to check if this is working you could have the following check:

if [ ${API_KEY} ] ; then 
    echo $API_KEY 
else
    echo "No API Key Found"
fi

Or you could also use the printenv command which would print all of your currently available environment variables.

Hope that this helps!

Regards,
Bobby