Ocultar barra de tareas

Aqui te mando un ejemplo de como hacerlo utilizando APIs, solo necesitas un boton Command1 en el formulario.
Pruebalo.
Option Explicit
Private Enum TipoAccion
SW_HIDE = &H0 ' Ocultar
SW_SHOW = &H5 ' Mostrar
End Enum
Private Declare Function FindWindowEx Lib "user32" Alias "FindWindowExA" _
(ByVal hWndParent As Long, ByVal hWndChildAfter As Long, _
ByVal lpClassName As String, ByVal lpWindowName As String) As Long
Private Declare Function FindWindow Lib "user32" _
Alias "FindWindowA" (ByVal lpClassName As String, _
ByVal lpWindowName As String) As Long
Private Declare Function ShowWindow Lib "user32" _
(ByVal hWnd As Long, ByVal nCmdShow As Long) As Long
Private Sub ShowHideTaskBar(ByVal Accion As TipoAccion)
Dim pTr As Long
pTr = FindWindow("Shell_TrayWnd", vbNullString)
If pTr = 0 Then Exit Sub
If Accion = SW_HIDE Then ShowWindow pTr, SW_HIDE Else ShowWindow pTr, SW_SHOW
End Sub
Private Sub Command1_Click()
Static Oculta As Boolean
If Oculta Then
ShowHideTaskBar SW_SHOW
Command1.Caption = "&Ocultar"
Else
ShowHideTaskBar SW_HIDE
Command1.Caption = "&Mostrar"
End If
Oculta = Not Oculta
End Sub
Private Sub Form_Activate()
Command1.Caption = "&Ocultar"
End Sub
'Suerte.