All teachers can self-manage the student logins within a course.  Click on the "Manage My Logins" link from your Teacher's Menu.  Then select the student name from the combo box and click on the "Manage User" or "Unenroll User" buttons.  

"Manage User" - allows you to edit the student's login name, first/last name, email address, and reset the student's password to a known default.

"Unenroll User" - will remove the selected student from your class.  If the student is not enrolled in any other course, their account will also be deleted.