How can i hide layers (eg the pin numbers layer) in the schem editor?
There is no real concept of “layers” in KiCad V5.1.7
(I don’t know about V5.99, have not used that yet).
But you may have noted that most schematic symbols have pin numbers, while others do not show pin numbers. This is a setting for each separate library symbol and can be changed with:
Footprint Editor / Edit / Properties / Annotations / Show Pin Number
No, not that, either. If the schematic editor would originally have been designed together with layout editor and shared code and concepts it could have made sense. Probably that’s the case with some other EDA packages. But IMO not now. We are talking about different kinds of items anyways, and even the layout editor has item type visibility.
In 5.99 there’s a way to set the visibility of all text items of certain type. Not exactly an on/off switch, but anyways.