title: Removing a user from backend created by IdentityServer4
body: <p>I am debugging confirmation email flow when signing up a new <code>User</code> in  Asp.Net Core web application with Identity Server 4.</p>
  
  <p>Since I had already signed up with my actual email, to reuse it, I modified the <code>UserName</code> and <code>Email</code> in <code>AspNetUsers</code> table using <code>SQL Update</code> to some random value.</p>
  
  <p>Now when I am signing up  with the original email again. I am getting a <code>duplicate user error</code></p>
  
  <pre><code>result = await _userManager.CreateAsync(user, model.Password);
  </code></pre>
  
  <p>I have already:</p>
  
  <ul>
  <li><p>Cleared browser cache.</p></li>
  <li><p>Closed local IIS Express</p></li>
  <li><p>Restarted Visual Studio.</p></li>
  <li><p>Used<code>_userManager.DeleteAsync()</code> after updating the <code>UserName</code> and <code>Email</code> back to original values but this gives an <code>Microsoft.AspNetCore.Identity.IdentityError</code> with description  <code>Optimistic concurrency failure, object has been modified</code>.</p>
  
  <p>On running this query on <code>Sql Server</code></p>
  
  <p><code>select * from INFORMATION_SCHEMA.COLUMNS where COLUMN_NAME in ( 'UserName' , 'Email')</code></p></li>
  </ul>
  
  <p>I get the following:</p>
  
  <p><a href="https://i.stack.imgur.com/8X5oY.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/8X5oY.png" alt="AspNetUsers"></a></p>
  
  <p>I know that this is not a good practice to mess with backend, but this is development environment and I could continue my work with another email.</p>
  
  <p>I would request readers to help in understanding how the <code>User</code> could be safely scorched to be able to reuse the email.</p>
  
  <p>Appreciate your time</p>