The only way to remove that is to disable the option to allow anyone with the link to view. You can however, test out the Json and see if you can remove that.
Go to edit on the dashboard, select Settings and click advanced settings. Once there select the Dashboard Json and see if that data is there and if you can remove it.
Im not 100% sure you can remove it but your best shot would be in the Json rather then turning off the no sign in required link.