There is no Scripting Guide planned, for PPro. Potentially comforting: there are >140 panels in use today that rely on PPro's ExtendScript API, and none of them had documentation either.
It is not possible, at all. Next-best thing: move old sequences into a bin you create, named something like "Andrei_says_to_delete_these".
Thank you,bbb_999! I try to do this. PProPanels is really helpful thing, but sometimes it seems you're deadlocked, and there's no way to solve the task.
Another way: close document without saving, and re-open it with basic structure (after exporting new seq to a .prproj). It works. But script creates about 1000 new sequences, and I don't know what is better for prefomance: collect them into a bin "Andrei_says_to_delete_these" or re-open document everytime.
Could you describe the whole workflow, from the user's perspective? [mail might be better; b b b at adobe dot com]