apagar.xml

   ...
   <Button
        android:id="@+id/room_btn_apagar"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginTop="32dp"
        android:text="@string/txt_apagar"
        android:visibility="invisible"
        app:layout_constraintEnd_toEndOf="@+id/room_btn_salvar"
        app:layout_constraintStart_toStartOf="@+id/room_btn_salvar"
        app:layout_constraintTop_toBottomOf="@+id/room_btn_salvar" />
   ...