During Lent and the days of December 17 to 23 inclusive, all obligatory memorials become optional. This means that no memorials are celebrated in the usual manner; rather, the full texts for the day must be recited.
If one wants to observe a commemoration, at Morning Prayer and Evening Prayer, they complete the whole Office for the day first, then recite the Benedictus/Magnificat antiphon, followed by the closing prayer of the saint. All, that, however is optional; there are no obligatory memorials or commemorations during Lent.