How remove dead dragon from scroll?

[Erra]

Not Undead, normal Dead dragon.

[Herk]

The shell will disappear after exactly 14 days on its own

[Soulsborne]

Tombstones from killed hatchies / adults ("zombie fodder" for most people) will do so as well.

[olympe]

And, no, there's no way to speed up the process. However, if the egg shells or tombstones bother you, you can always custom sort them to the end of your scroll so they're not quite as in-your-face.