How to delete an object?

[psphufi]

This building is doomed, it will be demolished within the next two years. I would like to show what this area will look like afterwards, but I cannot satisfactorily remove this building. There will always be artefacts of the sky in the background, which are disturbing.

It would also suffice if only the majority of the building is gone, for example to just above the mountain on the right.

Can someone please help me how to do that?

Thank you very much!

[Jean-Luc]

I mirrored the left part and deleted the bridge with the Clone Tool :

[psphufi]

This was a great idea, thank you! I would never have thought of that...