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
2017 F350 Lariat CCSB, SRW, 4x4, 6.7 PS
2017 Grand Design Reflection 337RLS