Problem after removing the plugin

Hi dear.
I overrided FormsAuthenticationService in my plugin for custom registeration.

The following form:
public class NewFormsAuthenticationService : FormsAuthenticationService
{
        public override void SignIn(Customer customer, bool createPersistentCookie)
        {
        }
}
As well as, I overrided CustomerController:    

public class NchCustomerController : CustomerController
    {
    }

When I delete the plugin,I can't log in anymore and still be used plugin.
I debug it,and i find out that Signin in my plugin runs insteadof original SignIn!

Please advice me,

Thanks.
[Best Regards]

I registered new service:
            builder.RegisterType<NewFormsAuthenticationService>()
                 .As<IAuthenticationService>().InstancePerLifetimeScope();