Unable to delete secondary admin user (CP Users)

Hello,

I am running ISPConfig 3 (current stable version).

Logged in as the main admin user, I created a second administrator account via:
System → CP Users → Add new user

This admin account was created only for testing purposes and existed only for a few seconds.
No clients, resellers, groups or other objects were created or assigned to it.

All modules/services were initially enabled, then all of them were disabled.
The account itself was also set to inactive.

Despite this, there is still no option to delete this admin user:
– no delete action is available in the CP Users list,
– and the account cannot be removed after editing it.

Is this expected behaviour for admin users?
If so, is disabling the account the intended and only supported way to remove an unused admin account?

Thank you.