Hello A.,
To answer to an old question, from 2020 and:
We can now use 'hide' or 'remove':
hide @unlinked
as:
@startuml
usecase UC1 as "do something useful"
usecase UC2 as "control state of cpu"
artifact RQ1 [
A requirement text.
]
artifact RQ2 [
Another requirement text
]
skinparam packageStyle rectangle
'all other elements are hidden
hide @unlinked
'only linked are shown in diagram
UC1 -- RQ1
UC1 -- RQ2
@enduml
If that can help,
Regards,
Th.