Why I cannot delete the VPN user in cloud authentication page?

[Deleted User]

When you attempt to manage the cloud authentication page to remove some unused VPN users and notice that the 'Remove users' button is grayed out, the first step you should take is to check your account privileges. Confirm that you have full privileges.

Secondly, please note that those accounts should be created at the organization-wide level. Please navigate to Organization-wide > Cloud authentication, where you will be able to delete those accounts.