I face this problem all the time. It's idiotic for people to put someone else's email id. This causes a lot of spam. However, I typically try to give them a chance to correct. If the spam still persists, I just go ahead and delete the a/c.
Besides, it would mean that the service (website) is so bad that they do not verify email ownership before allowing creation of the a/c with this email id.
Is there an option to just change the email address? Change it to mailinator.
We are not lawyers. You have a legal question. Find a lawyer, consult with the lawyer.
If it's someone you know, check with them beforehand.
It's most probably some random person who has a similar e-mail address, and they mis-typed it. For example, john.smith7@gmail.com mistakenly typed john.smith8@gmail.com.