How do I reassign my Administration Ownership from SAP Business Network?

You must be assigned with Administrator role.

1. Click [User Initials] > Settings > Users
2. Click Manage Users.
3. Select [username] you want to transfer the Administrator role to.
4. Click Actions > Make Administrator
   The Assign a Role page opens.
5. Select a new role for your account, and click Assign.

After the Administrator role is transferred to a new user, SAP Business Network sends a notification to the new account administrator, alerting them that they now have the Administrator role.

You may also refer to Transferring Administration Ownership for more details

SAP Business Network for Procurement & Supply Chain > Administration (Buyer & Supplier Account Administration)
SAP Business Network for Procurement & Supply Chain > SAP Ariba Supply Chain Collaboration