Remove redundant developer documentation on more OOP solution

docs/DeveloperGuide.md

@@ -132,12 +132,6 @@ and all associated `Appointment` objects (which are contained in a `DisjointAppo
 * stores a `UserPref` object that represents the user’s preferences. This is exposed to the outside as a `ReadOnlyUserPref` objects.
 * does not depend on any of the other three components (as the `Model` represents data entities of the domain, they should make sense on their own without depending on other components)
 
-<div markdown="span" class="alert alert-info">:information_source: **Note:** An alternative (arguably, a more OOP) model is given below. It has a `Tag` list in the `AddressBook`, which `Person` references. This allows `AddressBook` to only require one `Tag` object per unique tag, instead of each `Person` needing their own `Tag` objects.<br>
-
-<img src="images/BetterModelClassDiagram.png" width="450" />
-
-</div>
-
 
 ### Storage component