You can enable/disable from Ad-Aware GUI under Extras section.
Also it can be removed by opening Control Panel then open Add Remove Programs and select the Ad-Aware Email Scanner for Outlook.
I disabled mine through the "Extras" tab on the main AAW screen.
Reason: Everytime I started to download emails to Outlook, Outlook terminated completely. To get it going again, had to wait due to MS message "Outlook closed abnormally, scanning Personal Folder file for problems" which takes ages to get back to Outlook, then repeat the whole process again ! I wasted a whole afternoon dreading that my Outlook pst file must be corrupted, before looking though Outlook Add-ins and saw the AAW Email Scanner listed there - disabled it, and Outlook now works perfectly.
For extra safety, also disabled it in the AAW "Extras" tab.
I can do without add-ins like this. Clearly there are a lot of problems with it.