Sorry, nothing that I could provide that would be safe.
The problem is that all the search boxes for filters in the GUI are populated from the config. Web Reporter remembers every unique value it has ever seen (user names, client ip addresses, categories, groups, etc.). There are not any maintenance taks that try to clean these. Trying to manually remove them could leave your configuration in an invalid state that could cause more problems in the future.
It's just a current limitation. I'd strongly urge you to follow up with your sales contact and/or file a product enhancement request.
Doesn't appear that Web Reporter is an option, so McAfee Web Gateway would probably be the next best choice.
Thanks for the info I'll try an enhancement request, I have a few in mind.
My problem is a user may exist in multiple groups, we use a a number of Audit groups for reporting but some additional groups have been populated in reporter and if i exclude them in the filter it seems that it excludes the data for those users so I don't get an accurate report.