adding entries into combobox with code

[Transformer]

You have used userform1_Initialize and userform2_Initialize procedures to add items to Combobox2 and combobox3 but you didn't call them anywhere. Either write that code in UserForm_Initialize procedure or call these two procedures in UserForm_Initialize procedure.

Suggestion:
To fill the comboboxes,you add items to an array and then loop through the array to add items.You dont need to do that.It can be done in a single line.
e.g.

ComboBox2.List = Worksheets("Data").Range("B2:B15").Value

You can use the following snippet to disable the X button:

Private Sub UserForm_QueryClose(Cancel As Integer, CloseMode As Integer)
    If CloseMode = vbFormControlMenu Then
        Cancel = True
    End If
End Sub

Addendum:
If you want to avoid all the loops while filling the comboboxes than you can use the following code:

Private Sub UserForm_Initialize()
  
    ComboBox1.List = Evaluate("IF(ROW(1:15),TEXT(NOW()-8 + ROW(1:15),""mm-dd-yyyy""))")
    ComboBox2.List = Worksheets("Data").Range("B2:B15").Value
    ComboBox3.List = Worksheets("Data").Range("C2:C5").Value
    
End Sub