There is currently no way to reassign a finance authorisation task in Mosaic.
The workaround is:
From Team Summary, go to Authorisation Summary for the Element/Service level authorisation.
Choose Authorisation Action > Authorise and set Request Next Authorisation From to Team Lead, then save.
In the Team Lead’s Individual Workview, click the Authorisations button from the Current Work accordion and complete the Authorise Service/Element Level Authorisation task.
Go to Team Workview and open the Former Team Member’s Authorisation Screen to authorise the Care Package Level Authorisation task.
Reassign the Finance Care Package Step to the worker who will be taking over the authorisation.
Send the Authorisation Task again to the same worker.