I need to delete student paper submissions in an "assignment" because some just submitted their google link to the paper therefore it cannot be put into turnitin.com. How do I do this so they can submit their paper?
You can't remove assignment submissions from Canvas, but you also don't need to. As long as the assignment is still "open", students can always re-submit. When they do so the most recent submission is what you see by default, but you can also select previous submissions from a drop-down list in Speedgrader. I suggest simply typing a comment in Speedgrader back to the student letting them know that they need to re-submit the assignment. And, edit the Assignment, removing the option for them to submit a URL. If you want a file, only have the File box checked for Submission Type.
Here is a page from the Canvas Guides which might help
Can a student resubmit Canvas assignments?
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