Below is the full registry key for Outlook 2003’s PDF add-in:

Windows Registry Editor Version 5.00

1
2
3
4
5
\[HKEY\_LOCAL\_MACHINE\\SOFTWARE\\Microsoft\\Office\\Outlook\\Addins\\PDFMOutlook.PDFMOutlook\]  
"Description"="PDFMOutlook"  
"FriendlyName"="PDFMOutlook"  
"CommandLineSafe"=dword:00000000  
"LoadBehavior"=dword:00000002

To remove the toolbar, you can change the LoadBehavior from a 2 to a 1.