Most responsible people who do send unsolicited email usually provide a way to be removed from their list. Look at the beginning and end of the email to see if they mention any way to be removed. Another thing that you might want to do is look into your email clients method for automatically filtering mail.
Most email clients provide a way to automatically delete any email that meets certain constraints.
Please see your email client documentation for more information. As a last resort, we can refuse mail from domains that are known to send unsolicited email.