Taxi ribbons are useful at most airports, and I use them after landing, but cannot find a way to get rid of them once entering the gate zone.- At the assistance window they are enabled but greyed out. How can I do it ?

All I can say is that things were very different with the ribbons in the 2024 alpha. They disappeared when you were supposed to pause movement temporarily for instance. I'm not sure of all the differences in taxi ribbons between 20 and 24, there were other differences.