Practice.

what the fuck  
why is this an issue?

There isn’t an option too simply delete a post you made. The entire process is a bit involved, and is aimed at making sure that only the actual verified artist can remove art they don’t want posted here.
 
If you are the artist, then you submit a takedown request, found in the reporting tab under all the tags. From there, an admin will deal with it. You will need to have some kind of verified link to an outside site - deviantart, FA, etc in order to prove that the account you are trading under here is the same person who drew the art found on the other sites, and thus that you actually have the right to ask for a takedown of your work.

That depends. Did you make the picture? If so the FAQ has the answer. If it’s your upload but not your work, then you’ll have to consult the forums or IRC which is where questions like this belongs.