You can delete a post, but not a thread....only moderators can delete threads.
Under the post you want to delete, hit the edit button at the bottom right.
Next, click the "Go Advanced" button. At the top of the next screen, there is a delete button. There is also a "Reason for Deletion" button if you want to give an explanation.
Hope this helps.
Chap , DW Joy, and Fur Baby Sango
2006 Ford F150 Super Cab 4x4
2008 Surveyor 263