In the Agile Dashboard Planning view, since story #10759, there is a dropdown button on the backlog (left) side that allows to create "Parent" artifacts.

It was designed to allow people to create "Epics" (in the "standard" hierarchy Epics > User stories) easily, without leaving Planning view or having to hunt for the right Tracker. However, it comes with UX problems: contrary to the rest of the dropdown buttons, the created epics never appear on the interface (as they cannot be planned themselves). You can only choose them later when creating or editing User stories. The scenario for creating an Epic and linking a User story to it took two steps:

1. Create an Epic using the dropdown button
2. Edit a User Story (open the modal), search for the Epic created at step 1 and create a link to it

Since the completion of story #28823, the artifact modal allows the creation of new artifacts and their linking in one go. It is now possible to edit a user story and create its parent Epic in one go, all from the modal. This makes the dropdown button no longer useful: it takes two steps instead of a single one (with the modal) and it brings surprising effects that are bad for UX.

We should remove this dropdown button so that there is only one way to create and link parents: through the modal.

The dropdown button to add parents is removed.