For a Supplier's account to be closed they will first need to be removed or made inactive for all the Supplier Lists they are registered on. You can find information on understanding Supplier List registrations here: Overview of Supplier's List Registrations.
To provide this information to a Supplier, please use this link to the same article in the VendorPanel Supplier's Help Centre: https://vendorpanelsuppliers.zendesk.com/hc/en-us/articles/900002615766-Closing-Your-Account
For lists that they are registered on as a Colleague, they will need to ask their Vendor Admin to remove them as a Colleague. There is information here on how Vendor Admins can manage Colleagues: Suppliers Adding and Removing Colleagues.
For lists where they are a Vendor Admin, they will either need to transfer these lists to someone else or be removed/made inactive. As Supplier Lists act as a contract between Suppliers and the list-owning organisation, they will need to contact the List Owner (the Panel Administrator who manages the list) and request the list be transferred to another user or their profile be removed from the list.
You can find instructions on how suppliers can request to transfer a list to someone else here: How Suppliers Transfer a Supplier List to be Managed by another User.
Suppliers can find the List Owner’s contact details by selecting Supplier lists you manage under the Admin Tools menu (either in the top menubar or on the homepage on the left-side menu).
This page includes the details of the lists that are registered on as the Vendor Admin. They can click on the list name (in blue) to view the list’s details and relevant contact information.
Once they are no longer registered on any active lists, they can contact VendorPanel Support and ask to have their account removed.