note: I suggest using dashes instead of mixed case when trying to separate each word in a multi-word Passage Tag, it makes the resulting CSS class name more consistent with SugarCubes (and HTML in general) own naming conventions. eg. use "no-save" instead of "NoSave"
You can use CSS like the following within your Story Stylesheet area to hide the Save button on passages assigned a no-save tag.
body.no-save #menu-item-saves { display: none; }
... the ID of the Save button element was obtains from the HTML section of the SugarCube documentation.