create your query, then adjust the code for form, field names & combo box for yourself

query
SELECT ProductID, ProductName
FROM Products
WHERE ProductID NOT IN (SELECT ProductID FROM OrderDetails WHERE OrderID = Forms!frmOrders!OrderID);

dan in form current:
Private Sub Form_Current()
    Call RequeryComboBox
End Sub

Private Sub cmbProducts_AfterUpdate()
    Call RequeryComboBox
End Sub

Private Sub RequeryComboBox()
    Dim ctrl As Control
    For Each ctrl In Me.Controls
        If ctrl.ControlType = acComboBox Then
            If ctrl.Name = "cmbProducts" Then
                ctrl.RowSource = "SELECT ProductID, ProductName FROM qryAvailableProducts"
                ctrl.Requery
            End If
        End If
    Next ctrl
End Sub

I would add a Yes/No field to the table. In my example I named my field IsVisible in my Order table.
Add this field to your Query and set the criteria to True.
I also added a button to show ALL records.
Modify the code to your specific needs.

Example code:

Private Sub HideRecords(ShowRecord As Boolean)

    If ShowRecord Then
        CurrentDb.Execute "UPDATE OrderT SET Isvisible=True"
    Else
        CurrentDb.Execute "UPDATE OrderT SET Isvisible=False WHERE OrderID=" & OrderID
    End If
        
    Me.Recordset.Requery
    
End Sub

Private Sub Form_Current()

    HideRecords False
    
End Sub

Private Sub btnShowAllRecords_Click()

    HideRecords True
    
End Sub