Open your registry and find the key mentioned below. 

Create a new DWORD value, or modify the the existing value, named 'StartMenuLogoff'. Modify the value to equal '1' to enable the Log Off option or '0' to disable it. 

Exit your registry and log off for the changes to take effect. 

Note: By using the same key except under the [HKEY_LOCAL_MACHINE] tree the tweak can be enforced system wide, instead of only user based. 

Key:[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced]
Value Name: StartMenuLogoff
Data Type: REG_SZ
Data:0 = disable, 1 = enabled

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