The "Resynthesize" plugin for Gimp can automatically remove elements of an image. Of course the end results may not be perfect and require additional manaul editing.
Using the Lasso tool, outline the item you want to remove.
Go to the Filters menu> Map> Resynthesize> ok.
Note that: The "Resynthesizer" plugin will give good results when the following conditions are met:
Texture to be restored is not regular (clouds, earth ...).
Texture to be restored is present in significant proportions in the original image.
Texture to be restored is a simple one (contains few other textures).er.