No, your parents cannot stop you from going anywhere because in most States at the age of 18 you are considered an adult. If your parents may have good reasons why you should not go such as finishing your education then it would be wise to sit down with them and see if you can come to an amicable agreement such as going to Europe for a few months and then finishing your education and if you decide to do this and they agree then be mature enough to keep your promise.
