Once a meeting has been started, only the user who started the meeting can end it. Others will see the “End Meeting” button, however the button will not do anything for anyone who was not the user who started the meeting.
In other words, only the user who started the meeting can end it for all attendees.
This prevents one user from starting a meeting for a group and then one person in that group clicking “End Meeting” prematurely and kicking everyone out of the meeting.
You can discover who started the meeting by clicking on the “Activity Log” for the last user who started that meeting.
Update
Since Etho version 5.5.4, if the user who started the meeting is no longer in the meeting, anyone else still in the meeting can end it. Helpful for those meeting organizers who forget to end their meetings. You know who you are… 😉