c# - Remove an item from an IEnumerable<T> collection

Question

I have a popuplated IEnumerable<User> collection.

I want to remove an item from it, how can I do this?

foreach(var u in users)
{
  if(u.userId = 1123)
  {
    // remove!
  }
}

I know your not suppose to remove while looping, so I don't mind either creating a new collection or removing it after.

But I don't know how to remove an item, kind of lost for some reason on this!

Alternately which I am confused on also, how can I create a new collection like:

IEnumerable<User> modifiedUsers = new List<User>();

foreach(var u in users)
{
   if(u.userId != 1233)
   {
        modifiedUsers.add ??????
   }
}

How can I add to the collection?

Answer 1

Not removing but creating a new List without that element with LINQ:

// remove
users = users.Where(u => u.userId != 123).ToList();

// new list
var modified = users.Where(u => u.userId == 123).ToList();