By deleting a student's paper submitted to Turnitin you can clear the dropbox for them to resubmit: useful in the case of a mistake.
This refers to Moodle 3.6 from July 2019 onward.
By deleting students' submissions from your Turnitin dropbox, they will be able to resubmit, as long as it is before the due date or late submissions are enabled. This is useful to know if you have set the drop-box to only allow a single submission, as this method does not require you to change the settings of the drop-box.
Students themselves can replace submissions if resubmission is allowed - usually only up to the deadline.
It is not possible for students themselves to delete or replace submissions once the deadline has passed, or if the drop-box has been set up by the School not to allow resubmission.
The student can then resubmit PROVIDING it is still before the due date OR resubmissions are allowed. Note that the submission will bear the second date which may be marked as late: School processes should discount this if the student has permission for late submission.
The following other resources are also relevant to this topic: