Open Google Photos
Tap your profile picture or initial
Tap Photos settings
Tap Backup
Turn off Backup
If needed, turn off Back up device folders
On iPhone, go to Settings, then Photos, then turn off Backup if available in the app
On Android, you can also disable Google Photos app permissions or background data to stop uploads
To stop backup for a specific folder, open Back up device folders and turn off that folder
To stop backup completely across devices, sign out of the Google account in Google Photos or remove the account from the device