How to turn off @ mentions on IPBoard for inactive / cancelled members
You don't want existing, ACTIVE members to be able to tag former, INACTIVE members.
1 - You'll need a plugin by Nathan Explosion from the Invision Board Community which you can buy here for $5:
2 - Once you've purchased and downloaded the plugin login to your IPBoard admin area to install it.
Go to System => Plugins => Install new plugin
3 - Upload the plugin.
4 - Once the plugin is installed click on Edit:
5 - Select the user groups that you want active members to be able to mention and click Save.