Cannot find Registry Setting for Office Shared Templates

There is no way to do it from the Exchange system Manager, but you can give yourself FULL access to their mailbox, and the profile, and do it that way. Then you don't have to change the password. As Kara pointed out, instead of the profile, if you have outlook web access enabled (OWA), you can use that.

Please first go into ADUC (Active Directory Users and Computers), expand the domain, locate the Users, in the right panel, find the user that you need to set the Out Of Office.

Right click it, in the Exchange Advanced tab, click Mailbox Rights, confirm your account has the rights for read permissions and full mailbox access. Then click OK.

After that, please open Control Panel, locate Mail icon, double click it, click Show Profiles button, click Add button, then follow the wizard to create the user profile. When you are prompted to input the user account and password, please input your account and password instead of the user profile itself.

--http://social.technet.microsoft.com/Forums/en-US/...

Office 2013 Administrative Template files (ADMX/ADML) and Office Customization Tool

There are no ADM files for Office 2010+, you must use the ADMX files. It's usually easiest to place them in a Central Store for Group Policy Templates

Edit:
I think you might be trying to edit the local policy of a single machine; which is not recommended. However it does work to extract the ADMX folder, then copy it to %systemroot%\PolicyDefinitions. The next time you open gpedit.msc you should be able to edit Office settings for the local policy.