Yes / No is understood. But what will the cancelled option do?

Anyway, a very simple way to do this is

Code:
Private Sub CommandButton1_Click()
    
    If vbYes = MsgBox("Are you sure you want to delete", vbYesNo + vbQuestion, "Clear Cell Contents") Then
        Range("F7:L13,F18:L24,F29:L35").ClearContents
    End If


End Sub

But a more elaborate one which can be used to different actions based on response

Code:
Private Sub CommandButton1_Click()

    Dim vblResponse As VbMsgBoxResult
    
    vblResponse = MsgBox("Are you sure you want to delete", vbYesNoCancel + vbQuestion, "Clear Cell Contents")
    If vblResponse = vbYes Then
        Range("F7:L13,F18:L24,F29:L35").ClearContents
    ElseIf vblResponse = vbNo Then
        'Code here if user clicked no
    ElseIf vblResponse = vbCancel Then
        'Code here if user clicked cancel
    End If


End Sub