Upon reopening Word, you'll find the plugin is no longer loaded.
Open Mendeley Desktop and from the Tools menu select 'Uninstall MS Word Plugin'. Ensure you have quit Microsoft Word first. With Boomerang highlighted, click the '-' above the list to uninstall the add-in. If you are on an, , or email address, please click here, then select 'Boomerang' from your list of add-ins.The settings that affect mail are found in Personal Settings group as well as the E-Mail You can access these settings in the Outlook Preferences dialog, which you open by choosing Outlook→Preferences from the menu bar.