Remove members 'following this'

[Missing Lincs]

Is it possible to remove members for the list of those 'following' a topic?

I have some members following topics from years ago, there details aren't up to date so every time someone posts in the topic the forum tries to send them an email notification which fails.

Is it also possible to set topics so that they can't be followed?

The particular topic in this case is a 'container'  for other sub-topics.