A donor may choose not to have their donation amount or name appear on the campaing's list of donors.
Nevertheless, as an administrator of your own campaign, you will have access to their names, emails, pledge amount, etc.
We encourage you to reach out privately to your anonymous donors to thank them, but also to confirm that they want to remain anonymous for all public rewards. One way to do this is to write, "Hi NAME! I see that you chose not to have your name appear on the campaign page on StartSomeGood. Nevertheless, as an admin for this campaign, I'm notified about all donations, and I just wanted to say thank you for your generous support."