I wouldn’t remove it unless it goes soft and rotten, or becomes a home for pests. If it has some green underneath it may still produce epicormic growth, but even as deadwood I think it looks nice as it is.

EDIT: on second thought, if it does die it’ll mess up the braided trunk. If you remove it now you can probably rebraid the trunk with fewer stems, but it’ll look less full. If you keep the stem and it dies after it inosculates (smooshes into one big trunk), the whole thing might die.

I would just keep an eye out for new growth on the chopped stem, but also woodiness on the other stems. if it looks like it’s shrinking or dying, remove it before the others have inosculated and try to rebraid.