For example, if a Student Account was created for John Smith with the details:
And John created his own account with a scratchcard, with the details:
You could simply amend John's Account details as required. In this Scenario, you'd need to first change the details of the account you created (as you can't have duplicate Usernames or UserIDs within LabTutor):
Username: jsmith --> jsmith1
UserID: jsmith --> jsmith1
Username: john --> jsmith
UserID: smith --> jsmith
This also has the benefit of retaining all the Student's work.