I am fed up of scrolling for miles and miles to use the appropriate drum map. Sonar seems to load hundreds of maps by default.
I only ever have need for a few specifically those made for NI Battery and those made for Superior Drummer 2.
Everything else can go....so...where is the drum map list stored and how can I edit it down to just what I need?

The list is built on the fly from the Drum Map preset files in Your User Directory\AppData\Roaming\Cakewalk\Your Version of SONAR\Drum Maps. AppData is a hidden directory. Move files out of the directory to shorten the list.

The location is listed, and can be changed, in Preferences/File/Folder Locations.