Go to Class Module and click on a schedule.
Go to Registed Student Tab. Click on 3 dots for the student you want to remove and then click on withdraw student.
A pop up will come and from here you can select for what class the student must be withdraw. Just click on delete button to withdraw from class.
A pop will come showing you option to initiate refund first and then withdraw or you can just withdraw the student.
Finally you just have to put Withdraw Date and remarks and click on withdraw student.