Canon EOS 90D Advanced User's Manual page 351

Checkmarking [ X ] Images to Be Erased in a Batch
By adding checkmarks to the images to be erased, you can erase all those
images at once.
1
Select [3: Erase images].
2
Select [Select and erase images].
3
Select an image.
Turn the < 5 > dial to select the image

to be erased, then press < 0 >.
To select another image to be erased,

repeat step 3.
4
Erase the images.
Press the < L > button, then press [OK].

Erasing Images
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