Notice that the "remove the review keyword" step comes before the "merge the change to trunk" step.
Where is the place where these these steps are described and maybe I
am also not aware of other steps required after a branch is merged?
The reason you are not finding this in a list of steps after the branch is merged is because it should be done in advance of merging the branch, you skipped an earlier part of the process :).
Since the ticket is automatically closed, maybe the bot can also
remove the review ticket.
The review should be completed before the ticket is merged, so the bot should not be doing this automatically.
-glyph