I wouldn’t delete them. I wouldnt even lock them. They wont clog the forum up because the most recent posted things always appear first so they would just disappear into the ether which isnt an issue. Also it means they are still searchable using the forum search incase there is something useful inside the thread.
The only reason UKC delete the ‘Pub’ threads is because there are thousands of users which means a large amount of data so it would increase there storage costs. this wont be an issue for us as 1. Myles currently hosts it, 2.we wont get 1 days ‘Pub forum’ traffic in a year so the data usage is tiny