How to SetDirectory[] to the parent folder of the NotebookDirectory[]

Question

How do I SetDirectory[] to the parent folder of the NotebookDirectory[].

Concrete example

pretend I am typing code into notebook1.nb, what do I type such that the output of Directory[] is path/to/parent_dir/

+1 for elegant and easy to remember answer

Answer 1

You can use either

SetDirectory[ParentDirectory[NotebookDirectory[]]];

or

SetDirectory[FileNameDrop[NotebookDirectory[]]];