After installing an update for Outlook 2010 (KB3114409), Outlook start only in safe mode. The update is not available longer today. If you are the lucky one you got it early, you can still remove this update with the following steps:

Windows 10

  1. Go to Start, enter View Installed Updates in the Search Windows box, and then press Enter.
  2. In the list of updates, locate and then select update KB3114409, and then select Uninstall.

Windows 8 and Windows 8.1

  1. Swipe in from the right edge of the screen, and then select Search. If you’re using a mouse, point to the lower-right corner of the screen, and then select Search.
  2. Enter windows update, select Windows Update, and then select Installed Updates.
  3. In the list of updates, locate and then select update KB3114409, and then select Uninstall.

Windows 7, Windows Vista and Windows XP

  1. Go to Start, enter Run, and then select Run.
  2. Enter Appwiz.cpl, and then select OK.
  3. Use one of the following procedures, depending on the operating system that you’re running.
    1. Windows 7 and Windows Vista
      1. Select View installed updates.
      2. In the list of updates, locate and select update KB3114409, and then select Uninstall.
    2. Windows XP
      1. Select the Show updates check box.
      2. In the list of updates, locate and select update KB3114409, and then select Remove.

Or if you want to script it in a large deployment with Office 2010 Pro Plus, you can use the following from command line:

msiexec /I {90140000-0011-0000-0000-0000000FF1CE} MSIPATCHREMOVE={14CDCBF7-3CCC-42E2-A5BB-2D4926E16FAA} /qn

Source: Uninstalling Patches.

The notice posted on the KB page today:

After you install this update, Outlook 2010 may start only in safe mode. If this issue occurs, uninstall the update. This update is no longer available now.

Update: It is also possible to uninstall the update with wusa for all Office 2010 versions,

@echo off 
C:\Windows\System32\wusa.exe /uninstall /kb:3114409 /quiet /norestart 
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