1. First open the ppt slide, find the slide with watermark, and find all the watermarks that have been added.
2. Then, we click the slide master in the view options.
3. Click the slide master and find the first slide.
4. Click the inserted watermark, press del or backpace to delete it, and then close the slide master.
Edit shortcut keys
Ctrl+T: Change the character format between lowercase and uppercase.
Shift+F3: Change the case of letters.
Ctrl+B: apply bold format
Ctrl+U: apply underline.
Ctrl+l: apply italic formatting.
Ctrl+ equal sign: Apply subscript format (automatically adjust spacing)
Ctrl+Shift+ plus sign: apply superscript format (automatically adjust spacing)
Ctrl+ spacebar: Delete manual character formats, such as the following characters and superscript characters.
Ctrl+Shift+C: copy the text format.