ohh, I don't think u can delete those, I thought that u had multiple accounts like u have one for yourself and there is one for someone else that was using the and it was just there since that person didn't use the computer anymore.
But I don't really see any problem with those. I have my account, all users and default user (hidden folder). Ofcourse I use my account so I can't delete it but the other 2 use a total of under 30mb of hdd space so I don't see it as a problem. It shouldn't take more than a few seconds to scan it and u should not run out of space just because they take up 30mb of ur hdd space.
But ofcourse if those files get big (like 2gb) then it might start to be a problem, but they are not going to get that big unless u start throwing crap (as in movies etc.) in there.