This policy setting specifies how you want links on webpages to be underlined. If you enable this policy setting a user cannot choose when to underline links. You must specify when to underline links: • Always • Never • Hover (when the mouse pointer pauses on a link)If you disable or do not configure this policy setting the user can choose when to underline links.

1. Registry path is:

   HKEY_CURRENT_USER -> Software -> Policies -> Microsoft -> Internet Explorer -> Main # Anchor Underline

2. The Administrative Template path is:

   Windows Components -> Internet Explorer -> Internet Settings -> Advanced settings -> Browsing

* Making mistakes while changing registry values can affect your system adversely. We recommend you to create a System Restore point before making registry manipulation. If you're new to Registry Editor, read this beginner's guide.

** To locate the registry and administrative template path, checkout beginner's guide.