How to remove Google Photos app from iMac

See the following from Google support https://support.google.com/drive/answer/2375081?co=GENIE.Platform%3DDesktop&hl=en#zippy=%2Cmac

To stop syncing completely, you can sign out of your account.

1. On your computer, click Backup and Sync .
2. Click More   Preferences.
3. Click Settings.
4. Click Disconnect account.
5. Click Disconnect.

and

Uninstall Backup and Sync

After you uninstall Backup and Sync, you can still find your files at drive.google.com.

1. Open Finder and click Applications.
2. Drag the "Backup and Sync" app into the Trash on your dock.
3. In the top left of your screen, click Finder  Empty Trash.