deleting

I keep getting to a stage where it says that i have used my quota for uploading photos, so i go to the end of my attatchments & delete a page as an ongoing thing, just realised though that it looks like when you delete them it also of course takes them off the threads so anyone looking cannot...

Don't seem to be able to delete a thread that I put in the wrong sub-forum by accident. Am I missing something or am I just stupid? (No need to answer the last bit).