Unlike User Profiles, once uploaded, there is no easy way to update or delete Global Address Book entries other than manually, entry by entry. You might have imported a large spreadsheet only to find (by using the Data Checker) that you’ve created duplicate entries or even realize later that you want to slim down the GAB to “necessary” entries only.

Fortunately there is a great workaround.

1. First run a Backup of the whole database. Then Export the current Global Address Entries to a csv file (Both on the Maintenance tab). Check the csv file to make sure it’s good. You will need this later.
2. Go to the Sites Tab and create a new site. Call it whatever you want.
3. Go to the Transfer Tab and choose the site with the problematic GAB as the “Site to Transfer From”.
4. Put your new site in the “Site to Transfer To” box.
5. To empty the entire GAB, in the Transfer Options, click the “Select” button, choose “Address Entries”, highlight the entire list and click Finish. All of those entries will be MOVED to the new site. (To highlight the whole list, click on the first entry, hold the “shift” key and click on the last entry).
6. If there were more than 200 entries you must go back, click on “Next 200 Users”, highlight and then Finish to add these. If more than 400, repeat to the third page and so on.
7. Or you can just transfer selected entries (using ctrl or shift keys).
8. All of the selected GAB entries will be moved to the new site.
9. Go back to the Sites Tab and delete the new site you created. Those GAB entries are now gone. Important: All recorded names for the entries would have also been deleted.
10. If you emptied the entire GAB, open the csv file you exported, edit as desired and re-import the corrected info. Or just start from scratch.