SOLUTION1:1. Close Outlook.
2. Click Start run>
3. outlook /cleanreminders
SOLUTION2:Download MFCMAPI tool from
http://support.microsoft.com/?ID=2917941. Run MFCMAPI on the desktop
2. Go to Session > Logon and Display Store Table
3. Select your profile
4. Select Mailbox
5. Expand "Root Container"
6. Right click “Reminders" and select "Open Contents Table"
7. New window launches with Title Reminders
8. Select all the reminder items listed there, Right click and select "Delete Message"
9. Close MFCMAPI
Reopen Outlook.
Thank you....