This was up, but archived.  See Add, Create, or Modify a Calculated or the Total Column in the Gradebook.   Being able to calculate things in the grade book beyond adding things up or weighting and ad...

This doesn't answer the question. This shows how to give an additional attempt.We have a situation where we actually need to delete an attempt. (The quizzes are automatically scored, but optional. The...

You absolutely need to be able to delete quiz attempts and assignment submissions in Canvas. 

Just use the math functions you have in the quizzing engine (+-*/, sum, average, min max, etc) to allow people to create calculated columns in the gradesheet and use one of them to be the final grade....

All of this gets solved if you just give instructors actual control of the gradebook like any functional course management system would. Tom

This doesn't answer the question. This shows how to give an additional attempt.We have a situation where we actually need to delete an attempt. (The quizzes are automatically scored, but optional. The...

You absolutely need to be able to delete quiz attempts and assignment submissions in Canvas. 

How can this not be a feature of any learning management system?  The ability to share grading criteria to create consistency across classes is critical.  

You can solve this easily using records of deletion and it is a FAR FAR lower risk than the risk of releasing protected information.

Just use the math functions you have in the quizzing engine (+-*/, sum, average, min max, etc) to allow people to create calculated columns in the gradesheet and use one of them to be the final grade....