The only way to remove default gear in Phasmophobia is by replacing it with better items as you unlock them. You cannot completely get rid of your gear since you must have one of all default items ...

Krampus can be found from Dec. 12 to Dec. 31 in Phasmophobia. After the Winter’s Jest event ends, he’ll leave and all four holiday maps will go back to normal. No special ghost models from past events ...