Here is how one might go about hiding the taskbar:

Code:
 Private Declare Function apiFindWindow Lib "user32" Alias "FindWindowA" (ByVal lpClassName As String, ByVal lpWindowName As String) As Int32
    Private Declare Function apiFindWindowEx Lib "user32" Alias "FindWindowExA" (ByVal hWnd1 As Int32, ByVal hWnd2 As Int32, ByVal lpsz1 As String, ByVal lpsz2 As String) As Int32
   Private Declare Function apiShowWindow Lib "user32" Alias "ShowWindow" (ByVal hwnd As Int32, ByVal nCmdShow As Int32) As Int32
    
'event to hide
Dim tWnd As Int32 = apiFindWindow("Shell_TrayWnd", vbNullString)
        Dim bWnd As Int32 = apiFindWindowEx(tWnd, bWnd, "BUTTON", vbNullString)
apiShowWindow(tWnd, 0)'to hide taskbar
            apiShowWindow(bWnd, 0)'to hide startbutton
'event to unhide
Dim tWnd As Int32 = apiFindWindow("Shell_TrayWnd", vbNullString)
        Dim bWnd As Int32 = apiFindWindowEx(tWnd, bWnd, "BUTTON", vbNullString)
apiShowWindow(tWnd, 1)'to unhide taskbar
            apiShowWindow(bWnd, 1)'to unhide startbutton
Also you can make your form cover the whole screen(including taskbar) with this code:
Code:
 Me.WindowState = FormWindowState.Maximized