Delete freebusy via mfcmapi

Create a new Online Profile and select this profile when using MFCMAPI. O yes not to forget that you need to download mfcmapi tool from http://mfcmapi.codeplex.com/

1). Launch MFCMAPI.EXE, click "Session", click "Logon and Display Store Table" and
connect to the Outlook profile for the user.
2). Double click the "Mailbox - username".
3). Click "Root Container" to show the properties in the right-side pane.
4). Right click "PR_FREEBUSY_ENTRYIDS" and click "Delete Property" and click OK for
the dialog that pops up.
5). Expand "Root Container" and expand "Top of Information Store".
6). Click "Inbox" to show the properties in the right-side pane.
7). Right click "PR_FREEBUSY_ENTRYIDS" and click "Delete Property" and click OK for
the dialog that pops up.
8). Close all MFCMAPI windows and close Outlook.
9). Start Outlook from the Run line using the command: "Outlook /cleanfreebusy".

Also
1). Launch MFCMAPI.EXE, click "Session", click "Logon and Display Store Table" and
connect to the online profile.
2). Double click the "Mailbox - username".
3). Expand "Root Container".
4). Double click "Freebusy Data" folder.
5). Select the line which Subject is "LocalFreeBusy" and delete it.

Important: In the Deletion style select "Delete to deleted items" and click OK.

6). Close all MFCMAPI windows and close Outlook.
7). Start Outlook from the Run line using the command: "Outlook /cleanfreebusy".