Enrollsy does allow Admins to change the date someone enrolls. To do this, follow these steps:
Step 1 - Enrollee Tab
Head to the Enrollee's tab (by searching for their name in the top search bar or clicking on their name under the Enrollee/Table page or Class page).
Step 2 - Edit Enrolled Date
Under Programs, you will see their Enrolled date in the upper-right corner. Click the pencil icon to change the date and/or start time.