Welcome @LYNDAGRASSO to the Instructure Community! 🎉 I am so glad that you have joined us and hope that you continue to contribute.
Canvas is pretty jealous of information once students have seen it. An assignment that has submissions cannot be unpublished, so you can't select that option to hide it from students. However, you can hide the grades for that item by selecting the manual grade posting policy. That's explained in the Canvas Guides document How do I select a grade posting policy for a course in the Gradebook?
If you make a quiz a practice quiz, it should not appear on the Grades page for students or instructors, per the Canvas Guides document What quiz types can I create in a course?