I have some users in the private envirtoment that Yodlee provides, and would like to unregister, remove or delete them. Is this possible? if so, how?
You will have to use uregister API which Yodlee provides to remove an user.
If using SOAP - UserRegistration.unregister(UserContext userContext)
IF using REST - https://developer.yodlee.com/Indy_FinApp/Aggregation_Services_Guide/REST_API_Reference/unregister