Conversations among multiple participants for collaboration and communication in Teams
Hi Caroline Moroney,
If you meant how to disable private chat in Teams, please contact your Teams admin to help you disable chat. Please go to messaging policy under the Teams Admin center. Admin can apply the policy to you and then chat off there in that policy. Info about messaging policies here: https://docs.microsoft.com/en-us/microsoftteams/messaging-policies-in-teams
If you meant how to restrict 1:1 calls, configure a Teams calling policy and turn off the Make private calls setting.
If you have different scenario, feel free to let me know and I hope you can provide a screenshot. Your understanding is highly appreciated.
Best Regards,
Linda