RE: Removal Of Mandatory Field
1. You would need to change the attribute's property to 'Optional' / 'Business Recommended', then publish the change and then remove it from the form.
2. In case you are unable to change the attribute to the above, it means that the system prevents you from changing this field.
In such cases, the field needs to remain on the form. So, as a workaround, put it in a new section named 'Hidden Fields', then uncheck the 'Visible by default' of the form field and also, make the section hidden by default.
This would be the approved approach, instead of using a hack to remove a field that the system deems you need on the form.
Let me know if you need more details.
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Cheers!