How can I disable members of Teams to start call

MichelleHe Hello, not sure I understand your question but there are many meeting policies you can configure https://docs.microsoft.com/en-us/microsoftteams/meeting-policies-in-teams

If you talking about the lobby and perhaps only some meetings you can enter the "Meeting options" for the specific meeting and choose 'Only me' from the "Who can bypass the lobby" setting.

Change participant settings for a Teams meeting

https://support.microsoft.com/en-us/office/change-participant-settings-for-a-teams-meeting-53261366-dbd5-45f9-aae9-a70e6354f88e