I have mentioned a few times the “Twelve Days of Christmas” (which ended with the Feast of the Epiphany last week) and the need to celebrate the whole time. In any event, the Christmas season in the current liturgical calendar actually goes through today, the Feast of the Baptism of the Lord. So if you still have your decorations up, you have my permission (ha!) to take them down today if you want!
Even still, as I have also mentioned on various occasions, there is the old custom in some places – such as in the Vatican – of keeping decorations up until February 2nd, the Feast of the Presentation. So don’t feel bad if you want to keep your decorations up longer: you are in the good company of the Pope (and the Vatican is not the only place where this custom is observed)!