You cannot modify chunks of land. However, there is one exception:
-You can create islands to create your nation.
*However, the size limit of the islands must be the size of the Kingdom of Spain (that is, the islands must be moderately small); nobody wants islands taking too much space on the oceans.
You cannot modify any nations if they were not created by you; nobody wants their nation gone by the suggestion of another person; even if you do for the benefit of the nation.
*I was going to add the suggestion of RedSaz, but since the Republic of Chile was created by BluuStarz & not by him, he cannot modify it.