Open Google Photos on your phone or go to photos.google.com on your computer
Go to the album, search results, or date group containing the photos you want to select
On mobile, press and hold one photo to start selection mode
Tap additional photos to select them one by one
On computer, click the checkmark on a photo to start selection mode
Hold Shift and click another photo to select a range of photos on computer
Use the Select all option if it appears in the menu for that view
Scroll and continue selecting photos if no Select all option is available
Use the top action bar to delete, share, move, or download the selected photos