This is a user to user support forum, we choose to be here to answer user questions where they're applicable to the product; if you want guaranteed support from the vendor you need to be using Member Support
to receive support directly from the vendor, or seeking support from the person who has been providing support to you privately. These are not paid support forums.
You can move a post out of a discussion by clicking edit and "move/merge this post and any replies" option; note that on forums that use Quick Reply your replies aren't necessarily assigned to the post right above their response, so you'll likely end up having to move/merge multiple posts and attach them to a specific parent posting.
You can only delete one post at a time, you cannot delete multiple posts within a thread at once; what you see is what is available to you.
If you have users skirting how the system works, you'll need to ban them until you can sort their postings; the system currently attributes any posts made to a post count unless within a "posts don't count" forum (see the "Posts Count" option when editing a forum).
This is a product which was developed in the mid 90s; Isaac and I have only been providing updates to the base since v7.5.9. Significant changes take a lot of time to be written, and huge feature changes have already been introduced since we started officially working on the base product (versus providing modifications and features through UBBDev