On the forum index there is a link to view all watched posts. From there you can click on each post and click the Stop waching this post for replys link.
E-mails are only sent out if a reply is made after you visit a topic. If you wish to no longer get replys to a given post simply never visit it again. While visiting it you can click the link mentioned above to end getting replys.
If your waching a forum for NEW posts then you must visit that given forum and click the link as described above. The only difference is the word "forum" will be subsituted for post.
On every notification e-mail is a link to stop watching that given post/forum. Clicking this link will do the same as the method above has been described. If you wish to no longer get subscribed to posts automaticly when you make a reply then you may uncheck that setting in your profile by editing your profile.
__________________ Remember dont tap the glass, your fish will think you're an idiot-Anonymous mother