You can view your SURFconext profile on https://profile.surfconext.nl. This page contains an overview of the information that your institution can potentially pass on to services via SURFconext. You can also see which services you logged in to via SURFconext in the past, and which attributes were passed on to the service. Finally, you can completely remove your SURFconext profile on this page.
On this tab you can see all attributes that can potentially be passed on to services connected to SURFconext. SURFconext employs a minimal disclosure principle, which means that only the absolute necessary (personal) attributes are transferred to a service. In other words, the service can not ask for more information than strictly necessary to run the service. For example: a certain service only needs your email address to operate, while another service only needs to know if your a student or an employee.