10. To delete a custom slide layout, click the “Delete” button in the “Edit Master” button group to delete it. 11. Click the “Close Master View” button in the “Close” button group on the “Slide Master” tab in the Ribbon to close the slide master view.Tweet.. Click the “Insert Slide Master” button to insert a new slide master and its a ssociated slide layouts into the “Slides” pane. Select a slide master in this pane and associate a new slide layout with it by clicking the “Insert Layout” button. 5. Customize a slide master by selecting it in the slides panel.