vb.net - How to remove a used string

Question

Now, I want to remove the string in the .txt file that the user used. This is to make it invalid for use.

---

Thanks to Tim Schmelter for the corrected code.

If .txt file.Contains(stN) Then
    'Do anything here
    'Then I want to remove the string used.
End If

Answer 1

You have to rewrite the entire file:

Dim newLines = File.ReadAllLines(path).
    .Where(Function(l) Not l.Trim.Equals(stN, StringComparison.OrdinalIgnoreCase) )
File.WriteAllLines(path, newLines)

If you don't want to use Trim and the case insensitive comparison:

.Where(Function(l) l <> stN)

Edit: Are you using .NET 3.5? Then File.WriteAllLines does not accept an IEnumerable(Of String) but only String(). You need to create one from the query:

File.WriteAllLInes(path, newLines.ToArray())