Instructions apply to all versions of PowerPoint for Windows and Mac.
kick off the slide with the image to which you want to apply a transparent background.
A new tab,Picture Formatappears at the top of PowerPoint.

SelectRemove Backgroundfrom thePicture Formatmenu group.
Then, draw a line around the area on the picture.
In PowerPoint for Mac, selectWhat to keeporWhat to remove.

SelectKeep Changesto remove the background.
Sometimes, the image ends up with more or less transparency than you’d like it to have.
If so, repeat these steps.

PowerPoint saves all your changes and even lets you revert to the original, non-transparent version.
To export the picture with its background removed, right-nudge the image and selectSave as Picture.
From thePicture Formatmenu group at the top of the screen, selectColor>Set Transparent Color.
Mac 2011 users must chooseRecolorfirst, and thenSet Transparent Color.
Select an area of the picture that is the color you want to make transparent.
Photos and other complex images with multiple objects and similar color shades are difficult to edit in this way.
For difficult photos, you canuse Photoshop to delete the background.
The free editorGIMP works as well.
Select a preset transparency option or selectPicture Transparency Optionsfor more choices.
Tomake a shape transparent in PowerPoint, right-hit the shape and selectFormat Shape.
Expand theFillmenu and enter a value into theTransparencymenu or use the slider to adjust transparency manually.