Confusion over deleting threads older than...

[calorie]

As the vB license allows you to set up a private and protected test board, where you can install and test modifications, you might want to check out the auto prune mod here. If you don't want to test modifications, then you could set up your fourms with a 'Default View Age' so only X days worth of threads are shown by default, and then use the stock 'Prune Threads Manager' when you truly want to be rid of threads.