.nfs* files are related to NFS. They appear on an NFS server when a file is deleted, but is still open by a client. The server must not delete the file because it still needs to provide the data to the clients that have it open. On the other hand, the server must delete the file because the process that deleted it expects it to no longer exist. So the NFS server renames the file to a name that hopefully nobody cares about.
It’s no use to try deleting them: you’d be deleting a file that’s still open by an NFS client, so the server would only create a new .nfs* file to keep the data.
Eventually the client will close the files and the .nfs* droppings will vanish.