There may be occasions where you will need to upload a file on behalf of a student, either in the first case or as a re-submission for the student. You can do this in Turnitin, even if the assignment has been set up to be anonymous. The submission process itself is the same, however you may need to make adjustments before you can do this step depending on a few variables.
Step 1: Go into the Turnitin submission point
Step 2: Find the search bar that says Submit on behalf of student and type in the student’s name
Step 3: Select the student’s name
Step 4: From here you follow regular submission process – you can read more about that in the submission guide
You can follow this process even if the assignment is set to be anonymous.

Deleting a student submission
There may be occasions when you’ll need to delete a students submission before you can resubmit for them. The most common will be if a student has submitted a paper already, and the due date has passed. You may also need to delete a student submission if you have not allowed resubmissions for the assignment, but you still need to re-submit on behalf of a specific student.
Deleted files cannot be recovered, double-check that you are selecting the right paper and the right student. Be sure to keep track of any submission times for this file, as this will be lost as well once the file is deleted.
Step 1: Go into the Turnitin submission point
Step 2: Find the student paper you need to delete and click on the three dots to the far right, under the Options column
Step 3: Select the option for Remove from Inbox
Note: Please do not select Request permanent deletion. This is not usually needed, and should not be used if you are simply removing an accidentally uploaded student paper.
Step 4:Click Confirm in the pop-up asking if you are sure you want to delete the submission

Allowing late work
There may be times when you need to submit work on behalf of a student, but the due date has passed and the assignment was set up to not allow late submissions. When this happens, you’ll need to go into the settings, allow late submissions, submit the student work, then go back into the settings to not allow late submissions.
Step 1: Go into the Turnitin submission point
Step 2: Click on the cog wheel in the top right corner of the page
Step 3: Open the Optional settings
Step 4: Select the option to Allow late submissions and click save
Step 5: Upload the student assignment
Step 6: Go back into the cog wheel and optional settings
Step 7: Un-tick the box for Allow late submissions and click save

It is technically possible for students to submit late work during the window when you have allowed late submissions. However, the student would have to try to submit late in the exact short period of time when you made it available, so this is very unlikely. If you are still worried about this possibility, you can always hide the assignment from students while you upload the file, and then make it visible once you are done.