Got some parts I can’t get to so need to hide some of the Geometry including Hairs. Is there a way to do this ?
In edit mode you can hide parts of the mesh by selecting them and press h. With Alt+h you make them appear again. Is it that waht you mean? Hair should be hidden in edit mode anyway, no? Or are you asking about something different?
No … Trying to Comb hair in “Particle Edit Mode” and can’t get to certain parts, so need to hide some of the Geometry including Hair strands.
Ah, sorry, my mistake. Didn’t read the subject carefully enough 
Then, no, wouldn’t know of a way to do that. Might be the best you can do is x-ray mode and ‘hide’ hairs with ‘h’ (which keeps them visible but no longer editable).
You can save a selection of faces as a vertex group and paste them in Particle Settings> Vertex Groups> Density. However, this will distribute all particles across the new selection. Something like that should work via hide.
I am on 3.6.2. This issue still remains or I am missing something. Hiding selected faces works in sculpt mode, but not particle edit mode. This was the most recent relevant post I could find on the issue. I am surprised more people have not been bothered by this.