If you uploaded them, yes. Just go to User CP at the top, then manage attachments. You can delete the ones you don't want. Just know that if you delete one, it'll no longer be on your post that it was previously... so I'd opt for older posts or those that aren't very important.
"What, exactly, is the internet? Basically it is a global network exchanging digitized data in such a way that any computer, anywhere, that is equipped with a device called a 'modem', can make a noise like a duck choking on a kazoo." - Dave Barry