1.在注销方法中手动删除Cookies：

public IActionResult Logout()
{
    HttpContext.SignOutAsync(CookieAuthenticationDefaults.AuthenticationScheme);
    foreach (var cookie in Request.Cookies.Keys)
        Response.Cookies.Delete(cookie);
    return RedirectToAction("Index", "Home");
}

2.通过配置服务在注销时自动删除Cookies：

services.Configure(options =>
{
    options.CheckConsentNeeded = context => true;
    options.MinimumSameSitePolicy = SameSiteMode.None;
    options.OnAppendCookie = cookieContext =>
        CheckSameSite(cookieContext.Context, cookieContext.CookieOptions);
    options.OnDeleteCookie = cookieContext =>
        CheckSameSite(cookieContext.Context, cookieContext.CookieOptions);
});

public class AccountController : Controller
{
    private readonly SignInManager _signInManager;

    public AccountController(SignInManager signInManager)
    {
        _signInManager = signInManager;
    }

    [HttpPost]
    [ValidateAntiForgeryToken]
    public async Task Logout()
    {
        await _signInManager.SignOutAsync();
        return RedirectToAction(nameof(HomeController.Index), "Home");
    }
}

在Startup.ConfigureServices方法中，调用services.Configure方法进行配置。在注销方法中，调用SignInManager.SignOutAsync方法注销用户，系统将自动删除Cookies。