Now how to delete values and keys, but be warned you will need to take particular attention as using reading the following sections incorrectly could lead to the corruption of your computer. I will explain more about this below.

To be able to delete values from the registry you need first open the key and then use the RegDeleteValue API function, which has the following parameters:

hKey – This is the handle returned from the RegOpenKeyEx API function.

lpValueName – This is the key that you want to delete and its contained value.

Option Explicit

Private Declare Function FormatMessage Lib "kernel32" Alias _

"FormatMessageA" (ByVal dwFlags As Long, lpSource As _

Any, ByVal dwMessageId As Long, ByVal dwLanguageId As _

Long, ByVal lpBuffer As String, ByVal nSize As Long, _

Arguments As Long) As Long

Private Const FORMAT_MESSAGE_FROM_SYSTEM = &H1000

Private Const FORMAT_MESSAGE_IGNORE_INSERTS = &H200

Private Declare Function RegOpenKeyEx Lib "advapi32.dll" Alias "RegOpenKeyExA" (ByVal hKey As Long, ByVal lpSubKey As String, ByVal ulOptions As Long, ByVal samDesired As Long, phkResult As Long) As Long

Private Declare Function RegCloseKey Lib "advapi32.dll" _

(ByVal hKey As Long) As Long

Private Declare Function RegDeleteValue Lib "advapi32.dll" _

Alias "RegDeleteValueA" (ByVal hKey As Long, ByVal _

lpValueName As String) As Long

Private Const STANDARD_RIGHTS_ALL = &H1F0000

Private Const KEY_QUERY_VALUE = &H1

Private Const KEY_SET_VALUE = &H2

Private Const KEY_CREATE_SUB_KEY = &H4

Private Const KEY_ENUMERATE_SUB_KEYS = &H8

Private Const KEY_NOTIFY = &H10

Private Const SYNCHRONIZE = &H100000

Private Const KEY_CREATE_LINK = &H20

Private Const KEY_ALL_ACCESS = ((STANDARD_RIGHTS_ALL Or _

KEY_QUERY_VALUE Or KEY_SET_VALUE Or KEY_CREATE_SUB_KEY _

Or KEY_ENUMERATE_SUB_KEYS Or KEY_NOTIFY Or _

KEY_CREATE_LINK) And (Not SYNCHRONIZE))

Private Const HKEY_LOCAL_MACHINE = &H80000002

Private Sub cmdDeleteValue_Click()

Dim lKeyHandle As Long, lTemp As Long, _

sTemp As String, sTempLen As Long, _

sData As String, sDataLen As Long

' Declare variables to hold opened key

' handle and error information, etc...

lTemp = RegOpenKeyEx(HKEY_LOCAL_MACHINE, "SOFTWARE\MW-SOFTWARE", 0&, KEY_ALL_ACCESS, lKeyHandle)

' Open the key and return the handle to the

' lKeyHandle variable

lTemp = RegDeleteValue(lKeyHandle, "Rating")

' Call the RegDeleteValue API function to remove

' the key 'Rating' and its value from the opened

' handle of the sub-key

Call RegCloseKey(lKeyHandle)

'Call RegCloseKey(lKeyHandle)

' close the opened key by passing the key handle

sTemp = String(100, 0)

' Fix the length of the string

sTempLen = FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM _

Or FORMAT_MESSAGE_IGNORE_INSERTS, vbNullString, lTemp, _

0&, sTemp, Len(sTemp), ByVal 0&)

' Call the format message API function to return

' error information in the form of a string

MsgBox Left$(sTemp, sTempLen)

' Use the length of the error string returned

' to reduce the string back down to size and

' display the message in a message box

Now if you run the project, and click on the command button that the value will be deleted from the registry. You will need to make sure that the value

HKEY_LOCAL_MACHINE\SOFTWARE\MW-SOFTWARE and Key Name Rating exists in the registry.