Ghost image remains after selecting by color

[PosWeyb]

 I am not sure what I have done here.  I was attempting to remove some very faint graph marks on an image.  I used the select by color.  I then tried to delete what I had selected.  Instead I got this kind of ghost image.  I tried to move it and indeed it appeared to be a outline of what I was trying to get rid of.  But now it won't go away.   I even shut the program completely down, but it is still there.   I have attached a screen shot and the actual file.