I’m not clear on how to clear recent tags in the most recent version of the iOS app.
Recent tags should just be tags you recently used. If there are no tags in your app (including the trash), I think they will disappear from the list at that point like they will disappear from the all existing tags list. I don’t think any behaviour around this has changed in the latest release, but I may be wrong.
In previous iOS versions, the recent tags ran horizontally above the keyboard, and at the far right of the list you had the explicit option to clear recent tags. Now the recent tags are listed vertically in a drop down from the tags icon, and I see no way explicitly to clear the list.
That is correct, there is not currently a way to clear that list. Can I ask what the reasoning for clearing it is? As @sylumer pointed out, things drop of the list naturally as you use other tags.
I would say the reason is primarily aesthetic. Sometimes I simply like to start with a completely clean slate.