You can delete multiple students in your teacher account at once by doing the following:
1) Log-in to your EEi Account
2) Go to My Account and adjust the top grade to the grade of students you will delete & click Update Profile
3) Click End of Year
4) Run the first step - place a check next to the students you wish to delete.
5) Click on My Account (Do not run Step 2 as that will promote students to the next grade)
Repeat these steps changing the top grade to each grade you need to delete multiple students.