They don't seem to exist. I can pick individual threads on the front end, but what I need is the ability to go in and search for all threads that haven't been updated in x days, or all threads in a certain forum, or all threads that have been deleted, etc... and move them to a different forum or permanently delete them.
Oddly, I can't find this as a recommendation. A few threads talking about how the options don't exist and db queries to get the results someone needed, etc...
I think there are various suggestions, including mine, that an entire set of admin utilities is needed for everything from pruning members to pruning threads and forums.
Member management was my one stumbling block on moving - my old (2003 vintage) forum SW had all that stuff....but I think XF is attempting to get the framework and basics perfect - and then let future versions and add-ons fill in the rest.
Member and thread and forum management is definitely CORE, though.......so hopefully eventually we'll see it all.