Picasa allows you to add photo, rename, move folders from one to another folder on Mac. To delete Picasa folders, open "Picasa" on Mac and select the folder which you would like to delete. Simply right-click on the folder and select "Delete Folder..." option. Your folder will now be deleted. If the folder has previously been uploaded to Picasa Web Albums or Google Photos, then you will have the option to delete the online folder. To do so, simply you need to check mark the button located in front of "Delete online copies, too" option and then click "Delete Folder".