The Pro version also has a mechanism to manually remove enrollment. That is located at wp-content/plugins/tutor-pro/addons/enrollments/classes/Enrollments_List.php
There are two sections. One starts at line no 121 for cancellation and another at line 131 for deletion.
Please note that we have plans to organize this process in a better way to integrate with external systems. We will update this document as soon as the new system is available.