School and District Administrators are the only users who can delete student accounts.
Click Administration
Use the drop-down filters
Use grade and class filters to narrow your list of students to the group you would like to delete.
Select the students
Use the select all check box at the top of the left column to select all of the students in the list.
Click Delete
Confirm the account deletion
Click Delete from the confirmation dialog.
The selected students have now been deleted. You can restore these students and their data using the Restore feature described in How do I restore deleted student accounts?