Use RemoveAccessRuleAll method removes all rules that match user and AccessControlType, ignoring rights and flags. : RegistryAccessRule « Security « C# / CSharp Tutorial

1. C# / CSharp Tutorial
2. Security
3. RegistryAccessRule

using System;
using System.Security.AccessControl;
using System.Security.Principal;
using System.Security;
using Microsoft.Win32;

public class Example
{
    public static void Main()
    {
        string user = Environment.UserDomainName + "\\" + Environment.UserName;
        RegistrySecurity mSec = new RegistrySecurity();

        RegistryAccessRule rule = new RegistryAccessRule(user, 
            RegistryRights.ReadKey | RegistryRights.WriteKey
                | RegistryRights.Delete, 
            InheritanceFlags.ContainerInherit, 
            PropagationFlags.None, 
            AccessControlType.Allow);
        mSec.AddAccessRule(rule);
        rule = new RegistryAccessRule(user, 
            RegistryRights.TakeOwnership, 
            AccessControlType.Allow);
        mSec.RemoveAccessRuleAll(rule);

        ShowSecurity(mSec);
    }

    private static void ShowSecurity(RegistrySecurity security)
    {
        foreach( RegistryAccessRule ar in 
            security.GetAccessRules(true, true, typeof(NTAccount)) )
        {
            Console.WriteLine("        User: {0}", ar.IdentityReference);
            Console.WriteLine("        Type: {0}", ar.AccessControlType);
            Console.WriteLine("      Rights: {0}", ar.RegistryRights);
            Console.WriteLine(" Inheritance: {0}", ar.InheritanceFlags);
            Console.WriteLine(" Propagation: {0}", ar.PropagationFlags);
            Console.WriteLine("   Inherited? {0}", ar.IsInherited);
        }
    }
}