Choose not to mention is a phrase that implies that one has the option to not bring up a certain topic or subject. It is often used when someone does not want to talk about something, or when they feel it is inappropriate to do so. OMIT is a synonym for this phrase, meaning to leave out or exclude something. This phrase can be used in many different contexts, such as when someone is writing a paper and wants to leave out certain details, or when someone is having a conversation and does not want to bring up a certain topic.