Problem Definition

It is possible for customers to add participants from a service desk request.
It is however not possible to remove participants, for instance, if they have been added in error, or are no longer required as a participant.
Agents can also not remove participants from within a Service Desk request.

NOTE:

Looks like the option to remove request participants for customers from the portal is not available when the below option is chosen:

However, remove request participants from the portal is possible when any of the other 2 options are chosen.

Suggested Solution

Provide the option to remove participants from within Service Desk

Workaround

Participants can get removed from the JIRA view issue screen.
Customers generally can not reach this screen, the only option for them is to request the Agent to remove a participant