An owner of an organization can edit the handle of existing members (a pending member cannot be edited).
Handles are individual "tags" that allow members to tag other members within a Request. This allows for collaboration with other organizational members during the course of a Request's life cycle. When you "tag" someone using their handle in an internal comment, the tagged user will be notified by email.
Can Handles be changed after they are set?
An owner on the organization can update a handle. Also, you can reach out to Support@SeeClickFix.com to request a handle change.