Get rid of thin pic border after Crop

[GMP]

Actually I used the free select tool to crop the pic not the crop tool - sorry my mistake. I wanted to keep the inside of the pic, but when I hit delete, it deleted the inside and not the outside. I think there's a way to reverse it where it deletes the outside of the pic. Can that be done? I ended up selecting the part outside the pic so the selection had what I wanted to remove and that worked.