How to end a meeting for all

I tried all the options by enabling lobby, present me only and cancelling the meeting etc. But, even I cancelled the meeting also that will be available in the student's calendar and they are connecting to that meeting. A lobby is enabled that student will be in lobby waiting for admission by the organizer. But for other students, it shows as 2 meetings are there. Then some students are joining in the actual meeting and some students are joining in the removed waiting and complaining that no one is admitting them into the meeting. 

I am most irritated by these multiple meetings and unavailability of hard mute. For my parent feedback response sheet. 75% of people are very much satisfied with the teams. But 100% of parents are disgusted with thee two options.