Hello my name is ***** ***** computer professional with over 10 years experience. I will be happy to help you.
In some company networks with their own mail servers it is possible to recall an email if the email server allows it. That is why you may have seen some reference to doing this online if you searched around.
Unfortunately in your case it is not possible to recall an email after it has been sent since you are not in the same network as the person you were sending to. There is no time in transit and when you clicked send the email is already in the other person's inbox nearly instantaneously. Your account no longer has control over that message once it is sent.
The only thing I can suggest is to send another email explaining that it was sent in error. Another technique I tell people in this situation is to send a bunch more emails all with the same subject as the one you want to recall. Send at least 10 and the person who receives it will likely think this is an error and will not read the original as it will be buried at the bottom of the others you sent. That is unfortunately all you can do, you cannot recall the email. It is the same thing as if you called someone and left them a voicemail, there is no way to "unleave" the voice mail because it is now stored on their phone and waiting for them, you do not have control over it.
Your best bet if you really do not want them to read the email is to send a bunch more emails with the same subject to bury the original. Then later you can say there was an issue on your end and they were sent by mistake.
Please do me a favor and take a moment to rate my service by clicking the stars above, 3 or more is very appreciated, we can still chat after rating if you need more help. Thanks,Chris