Making a second account

I am teaching a sat prep class where half of the students had my class last semester and half are new. The students from last semester made accounts and recorded their test scores. Based on these scores a practice was set up for each individual student based on ability 1-4. I had students practice these skills until they had a 4 in the grammar section because I am a math teacher. I need to reset their scores but the only way I have found to do that is to make another account. However, when I type in the email address it says I have already created an account and will not allow me to make another one using that email address. Any ideas on how to fix my issue?