You can remove your joint accounts from an active Data Sharing Arrangement.
To remove your joint account for an active data sharing arrangement, go to Manage data sharing > Data sharing arrangements. Select an 'Active' arrangement. Select the 'bin' icon next to your account to remove it.
You can not add a new account to an active Data Sharing Arrangement. If you wish to amend your data sharing - contact the accredited third party for more information.