I spent a good bit of time fiddling with infoboxes on my personal wiki, and so have a lot of useless templates that clutter up my infobox list and need to be removed. But after deleting the template page, they still appear as an option in the insert->infobox option. Is there any way to fix this?
If a list takes more than about 2 days to update, report your problem to Special:Contact/bug from your wiki. These lists stop updating often, because Fandom supports thousands of wikis and apparently doesn't have any monitoring for when the updating of these lists stops working.