How to remove a mandatory field?
If you ever make a field mandatory when you import your list, you won't be able to edit this condition to non mandatory. To remove this condition without deleting all the statistics related to this field, you'll have to follow these simple steps:
Firstly, export your list so you don't lose any data.
Go into the Manage list section and click on the View and Edit icon. At the bottom of the page, under the section Next available actions, choose Export to CSV-All data.
Secondly, you have to erase the field and recreate it with the same exact name as before, be careful to not make it a mandatory field.
Go into the Manage list section and click on Manage in the actions column and then Save and continue, once at this page, you will be able to enter the new field .
You can also go to the view and edit icon of the actions column, at the very bottom of this page you will see a section called Next available Actions where there will be an action named add/edit fields. You will be able to delete the field and recreate it.
Finally, all you have to do is to import the list again to update the field.
And there you have it!