I am looking for one plugins in elgg 1.8 which can delete multiple posts / users using admin access.
Or any SQL query for the same. If i delete only users, their posts/n other reference may left behind.
There's a version of the bulk_user_admin plugin for Elgg 1.8 available at https://github.com/brettp/Bulk-User-Admin. This plugin would allow you to display user accounts sorted by the email domains used at account registering and then selecting multiple users to be deleted at once. You should take a look at this plugin (you need to rename the folder to bulk_user_admin after unzipping). Though you might start using it with care as I don't know if there might be some unfixed issue in the github version at the moment (which might be the reason it has not yet been released here on the site).