Outlook stores a number of recently used lists, from other users mailboxes, to locations, and recent searches, and stationery lists.
If you want to clear the list, you need to delete the appropriate registry value. Because the values are stored in binary format, you can't edit the list to remove some entries from it, only delete the entire list. The next time Outlook is used, it will recreate a blank key.
Outlook 2013 and Outlook 2016's MRUs are listed at Clearing Outlook's Most Recently Used (MRU) lists
MRUs under the profile key
In Outlook 2010 and older, navigate to the profile key, found at:
HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Windows Messaging Subsystem\Profiles\profile\0a0d020000000000c000000000000046
|MRU list:||Value to delete from 0a0d020000000000c000000000000046|
|Actions, New Mail Using, Stationery list||101f035e|
|File, Open, Other Users Folders (OL97/2002)||101e0384|
|File, Open, Other Users Folders (OL2003)||101f0390|
|Move to Folder history||101f031e|
|Save Sent Items folder list||101f0449|
|Insert, Signature dialog of the Outlook editor||101f035c|
|Find Contact (Outlook 20072010)||101f0446|
|Insert > Business Card (in compose message)||101f042b|
MRUs under the Outlook key
Note that in Outlook 2013, the Profile key is now under this key.
Navigate to :
where xx is your version of Outlook.
The Fonts MRU list is stored in the SettingsWordMail value in HKEY_CURRENT_USER\Software\Microsoft\Office\xx.0\Word\Data. I'm not sure exactly what else is in the value, but you need to delete the value to clear the Fonts MRU.
Do It For Me
If you don't want to edit the registry yourself, you can download and run the reg file for the key you want to delete. Make sure you choose the correct version and remember to restart Outlook for the key to take affect.
Appointment Locations (LocationMRU): Outlook 2013 | Outlook 2010 | 2007 | 2003 | 2002
Advanced Find's Search for Words (MRU 1): Outlook 2013 | Outlook 2010 | 2007 | 2003
Advanced Find's More Choices, Categories (MRU 3): Outlook 2013 | 2010 | 2007 | 2003
Choose Form dialog (Office Explorer \ Namespaces): Outlook 2013 | 2010 | 2007 | 2003
How to use the Registry Editor
Many of the Most Recently Used (MRU) lists in Outlook can be deleted by editing the registry. Quit Outlook then open the registry editor from the Start menu, Run command by typing regedit, and then click OK.
Navigate the left pane of the registry editor, looking for :
HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Windows Messaging Subsystem\Profiles\
Outlook Version numbers are as follows:
|Popular Name||Version Number|
Once you locate the proper set of keys, use File, Export to back up this section of the registry. If you are worried you made a mistake, you can double click on the *.reg file to restore it. Next, browse for the specific keys mentioned above. Select the value on the right side and delete it.
MRU's in other applications
If you need to delete MRU list in other windows applications use the Registry Editors Edit, Find menu to look for the keyword "MRU".