You may close a thread as long as you are the person who originally created/opened it. If you would like to close your thread:
Please navigate to Thread Tools-->Close Thread.
Once the thread is closed, you should see a Closed icon above and below your first and last posts.
If you are having issues finding the Thread Tools menu or confirming your thread is actually closed, please review the images attached to this post prior to contacting the moderators.
Thanks!
