Remove from Picasa: Prevent Picasa from scanning in a certain location
When you have pictures that you don't want to appear in Picasa, you should use the "Remove" feature to exclude them.
Example: Let's assume that you have a folder in My Pictures called "Junk".
1. Select Tools>Folder Manager
2. In the Folder List, scroll to the folder "Junk" that you want to remove and choose "Remove from Picasa"
3. Click OK
4. Picasa will remove "Junk" and all its subfolders
The folder "Junk" and all pictures within it will no longer appear in Picasa unless you change the setting.