Pentax K-R Operating Manual page 25

You can delete multiple images in the multi-image display at once.
Deleted images Cannot be restored,
,Protected images Cannot be de!eted:
• You can select up to 100 images at a time.
1
Turn the e-dial to the left (toward
[]) in Playback mode.
The multi-image display screen appears.
2
Press the _.UP/'_ button.
The screen to select the images to delete
is displayed.
The screen temporarily changes to 36-
image display when [Multi-img Display
Setting] (p.224) is set to 81-image
display.