Exchange 2013 - Should Flash Player be installed?

Absolutely not, Adobe Flash Player in my opinion should not be installed anywhere(very zero day heavy). I would take smart backups before removing it though. It could kill your server.

Should this be installed?

you shouldn't have it on servers
some management products (like vmware) require flash to manage the UI but exchange is not one of them; such tools should be managed from a desktop

However I don't see it in Programs and Features.

check \windows\system32\macromed\flash folder
if not, ask them where they found it installed

I just read that it was part of a Windows feature called Desktop Experience, and that's a pre-requisite for Exchange 2013 install......?

https://technet.microsoft.com/en-us/library/bb691354(v=exchg.150).aspx

is it a single CAS setup? I built one before and if it had flash i was completely unaware and only software required were two specific updates.

i couldn't find it in the link you posted either

this is a DAG with 6 nodes, each have the CAS role.

My install i mentioned no flash was on 2008 R2 which would explain that I guess.

thanks ALL