If you have successfully sold your item, or simply wish to take it off the market, we will not delete your post.
The reason for this is to help build trust in the classifieds section so users feel comfortable buying and selling here. The more successful "sold" posts that are present, the more willing people will be to use the section to sell and/or buy their own goods, which is the entire purpose it serves.
Instead of trying to delete your post or asking one of the mods to do it, please simply:
1) Go to your thread and click 'Modify' on your very first post.
2) Change the title to read '!!SOLD!!' (or some variant of). However, do not delete your original title!! Please just add '!!SOLD!!' to the beginning. I.E., if your title was 'FS: OEM Crosstrek Tires Set of 4', your edited title should simply be, '!!SOLD!! FS: OEM Crosstrek Tires Set of 4'.
3) Edit the body of the your thread. Again, we would like it if you didn't delete the content of the body, but rather just put a message in big, bold, red letters at the top that says something along the lines of
'ALL ITEMS HAVE SOLD'
Also, if you are selling multiple items in one thread and some have sold, please edit the body of your post to reflect that.