I've been thinking about deleting my Amazon freebies too -- but just the ones I've read and don't want to reread. I try to be selective with what I choose to "buy", but because they are free, I'll also take chances I would never have taken with paid books. Some are gems, some are ones I wish I'd left alone.
Now my husband has been buying the kids Kindles and I've been buying books for them from Amazon (I buy books for myself in epub, not from Amazon) -- it's too hard to keep track of their books, the audible books that Amazon dumps into my Kindle library AND the overwhelming number of freebies.
I'd like to be able to separate my purchases from my freebies, but I don't know of any way to organize my Amazon archives. Also, I'm a book hoarder so simply deleting books from my account puts me into a panic.
I'm going to do it though; my Amazon account has 1067 items in it -- a small number compared to some others, but I don't want to have to manage that many unimportant items (it would be different if I *wanted* to go back and re-read them.) And I do have to manage them -- it's compulsive.