Hi,
If u want to clean any .dll ext files ...there is a application that can help u in it.. U can try "Advanced System Optimizer"..
Its tool System Cleaner can remove all the temp files from the all users profile and here u can even choose the desired ext to be removed.
You should try this as this is what you want
Works gr8 ..!& its also got some other best optimizers & not so expensive..
Get it Here