Important: If you turned on iCloud Drive for Keynote (in System Preferences on your Mac), deleting a presentation from iCloud Drive removes it from iCloud and from all other devices and Mac computers that use the same Apple ID.
If you don’t know where the presentation is, locate it first.
Select the presentation, then do one of the following:
Drag the presentation to the Trash icon in the Dock.
Press Command-Delete on the keyboard.
To empty the Trash (and permanently remove the presentation from your computer), click and hold the Trash icon in the Dock, then choose Empty Trash.