You have the right to close an auction earlier.
If someone already bid on it, you first have to
cancel the bid, saying why you are doing it.
The reason isn't realy important : you are allowed
to change your mind and decided not to sell the item
anymore. You may remove the item because you mistook
it for something else when listing it. You may got
a trade offer or a buyout price that you decided to
accept.

It happens quite often actualy... Especialy when
people decide to trade : there isn't much point in
puting a dummy amount just to get the highest bid :
that would only result in the seller having to pay
a higher fee too ebay.

Cheers,
Yann Stettler