To Add, Edit, or Remove Players:
Log in to your Premium account, click on the Premium user ID in the top right and select "Your Students/Your Children". To add students, click on the blue "Add Student(s)" link and you can then manually add names, upload a spreadsheet, or import from Google Classroom. Once you add the first name, if you choose you can also add more than one child by selecting "Add another name", or you can select "Next Step" to enter the grade level for the child.
To edit a student, click the pencil icon to edit your child's name, avatar, or grade. You can also "Lock" and "Hide" individual student grade levels if you choose. To delete players, hit the trash can icon in each student's row, or you can delete a whole class by selecting all Students and then "Delete".
To edit a Group, click on the Premium user ID and select "Your Groups". You can then add, edit, or delete your groups from there.