how to delete identity users on delete cascade? - asp.net-core

Question

I am building an application using ASP.NET CORE 3.1 and built identity using built in funcations. When I delete or update I want to delete users and related entities from aspnetuserroles and aspnetusers.
I made an update users but seems verbose and I cannot make it work yet with a postman error.
Error
405 Method not allowed
I can sort this error out but I think the code is too verbose. Do you have any examples or a better way to do this?
Postman request
{
"email":"user#gmail.com",
"password":"Passw0rd",
"username":"user4",
"roles":["user"],
"firstname":"user",
"lastname":"Lee",
"phonenumber":"12345"
}
postman url
https://localhost:4200/api/accounts/05ce20c6-e2c4-4d40-b364-85c03206d562
Update Users
[Route("accounts/{id}")]
[HttpPut]
public async Task<IActionResult> UpdateUser(string id, [FromBody] RegistrationViewModel model)
{
if (!ModelState.IsValid) {
return BadRequest(ModelState);
}
var user = await _userManager.FindByIdAsync(id);
if (user == null)
{
return NotFound();
}
var userRoles = await _userManager.GetRolesAsync(user);
IdentityResult roleRemoveResult = await _userManager.RemoveFromRolesAsync(user, userRoles);
if (!roleRemoveResult.Succeeded)
{
ModelState.AddModelError("", "Failed to remove roles");
return BadRequest(ModelState);
}
IdentityResult roleAddResult = await _userManager.AddToRolesAsync(user, model.Roles);
if (!roleAddResult.Succeeded)
{
ModelState.AddModelError("", "Failed to add roles");
return BadRequest(ModelState);
}
//finished the role removing and assinging new roles
IdentityResult passwordResult = await _userManager.ChangePasswordAsync(user, user.PasswordHash, model.Password);
user.Email = model.Email;
user.FirstName = model.FirstName;
user.LastName = model.LastName;
user.PhoneNumber = model.PhoneNumber;
user.UserName = model.UserName;
IdentityResult updateUser = await _userManager.UpdateAsync(user);
if (!updateUser.Succeeded)
{
ModelState.AddModelError("", "Failed to update a user");
return BadRequest(ModelState);
}
var newUser = new User_Role_ViewModel();
newUser.Id = id;
newUser.Email = model.Email;
newUser.FirstName = model.FirstName;
newUser.LastName = model.LastName;
newUser.UserName = model.UserName;
newUser.Roles = model.Roles;
newUser.PhoneNumber = model.PhoneNumber;
return Ok(newUser);
}