Open the Group Clashes window by clicking on the Group Clashes button 

• Select a clash test. The two selections involved in the clash test are displayed below.
• Select one or two clash rules. Since Autodesk® Navisworks® Manage does not support subgroups for clashes, the group name will include the result of the two rules.
• Click on Group.

For a full description of each grouping rule, visit bim42.com.

The installer that ran when you downloaded this app/plug-in from Autodesk App Store will start installing the app/plug-in. OR, simply double-click the downloaded installer to install the app/plugin. You may need to restart the Autodesk product to activate the app/plug-in. To uninstall this plug-in, exit the Autodesk product if you are currently running it, simply rerun the installer, and select the "Uninstall" button. OR, click Control Panel > Programs > Programs and Features (Windows 7/8.1/10/11) and uninstall as you would any other application from your system.

Group Clashes is open-source. It will find the entire source code on Github, and start building your own grouping rules.

The Group Clashes app can have difficulties managing clash reports with more than 10000 clashes. Be smart when you set up your clash tests, and everything will be fine.