German Shepherd dog

Good Evening all,  has anyone ever started a picture gallery on their dogs and forgot to size a picture or put the wrong picture up?  Do you know if there is a way to delete the wrong picture or correct it and add the correct picture? I'm trying to do a gallery on my male  but messed up and forgot to size some and put up the wrong ones a couple of times.

Any help will be appreciated.

Thanks

Debbie