How to: Delete all text in a placeholder.
Solution:
In 'Slide' view, select all the text within a text box, and either press DELETE or select the 'Edit' menu and select 'Clear'.
1) Select the 'View' menu and select 'Slides'.
2) Select the desired text box. (Handles appear around the border.)
Selected placeholder
3) Select the 'Edit' menu and select 'Edit Text Object'. (A selection box appears around the border.)
Selection box
4) Select the 'Edit' menu and select 'Select All'. (All of the text within the selected text box placeholder is highlighted.)
Highlighted text
5) Do one of the following:
a) Select the 'Edit' menu and select 'Clear'. (The text is deleted.)
b) Press DELETE on the keyboard. (The text is deleted.)