Congress can disestablish courts, but it cannot remove judges except by impeachment and conviction. So, the court/seat on the court will exist for the remainder of the career of whatever judge sits on it.
It's not exactly clear. Certainly the judge is appointed for life, but the court itself has no such protection.
Likely Congress can make the court disappear, giving the judge no facilities, clerks, or staff, or anything else except pay. Such a judge would be in a world of hurt.