Вот несколько способов удаления символа из строки в VB.NET:

Метод 1: использование метода String.Replace

Dim input As String = "Hello World!"
Dim character As Char = "o"
Dim output As String = input.Replace(character, "")

Метод 2: использование метода String.Remove

Dim input As String = "Hello World!"
Dim index As Integer = input.IndexOf("o")
Dim output As String = input.Remove(index, 1)

Метод 3: использование цикла и StringBuilder

Dim input As String = "Hello World!"
Dim character As Char = "o"
Dim sb As New StringBuilder()
For Each c As Char In input
    If c <> character Then
        sb.Append(c)
    End If
Next
Dim output As String = sb.ToString()

Метод 4. Использование регулярных выражений

Imports System.Text.RegularExpressions
Dim input As String = "Hello World!"
Dim character As Char = "o"
Dim pattern As String = Regex.Escape(character.ToString())
Dim output As String = Regex.Replace(input, pattern, "")