Specifically as to your question, there is no way to make LinkedIn 'forget' the data. When you agree to sync your email connections, LinkedIn then sends one email to every address in your email contacts (even if you once sent an email asking for a refund on something - the system has no way of knowing who is and who is not important to you). After this first time, 2 more emails are sent reminding your email connections that you want them to join you on LinkedIn. So, each email connection receives a total of 3 reminders 'from you' asking to join you on LinkedIn.
You can rescind these emails by going to your Sent folder of your LinkedIn inbox and manually, one by one, deleting the requests. It is painful and tedious, but is currently the only way to stop these emails from going out.
There is no legal recourse, because you agreed to allow LinkedIn to take these actions when you agreed to sync your email with LinkedIn. It is there, in the fine print.
You certainly could, as suggested by another responder, delete this account altogether and begin again. If you do not have many valuable 1st connections, it may be your best bet. Be sure to use a completely different email address to set up the new account! And be sure to completely delete the old account, as it is a violation of LinkedIn user rules to have more than one account.