what is the 'Clear Selected Artboard Guides' in the Photoshop 'View' menu. I would like to use it but it is grayed out. I need to delete a specific guide from my artboard but moving it off the canvas just moves it off the canvas - it doesn't delete it. Thanks.
The "Clear selected artboard guides" menu item will be greyed out unless you have a document with at least one artboard, and you must also select one of the artboards for it to work. It allows you to clear all guides, but only those guides placed on the selected artboard.
Note that in Photoshop, if you create a new document using one of the Web or Mobile presets, it will generate a document with an artboard automatically. All the other new document presets will not. For these you will only get a canvas, rather than an artboard. You can of course create artboards for any document using the Artboard Tool.
If you want to delete a specific guide, or if you don't have any artboards, click and drag the guide and drop it on the ruler.