In Dynamics 365 Customer Service, the fields that appear in the ribbon bar are typically read-only and cannot be modified directly. However, you can adjust the mandatory/optional status of the Resolution field through the form editor.
Here are the steps you can follow:
1. Open the form editor: Navigate to the entity form where the Resolution field is located, and open the form editor.
2. Select the Resolution field: Locate the Resolution field in the form editor, and select it.
3. Edit the field properties: In the field properties window, find the "Business Required" property, which determines whether the field is mandatory or optional.
4. Change the Business Required property: Change the "Business Required" property to "No" to make the field optional.
5. Save and publish the changes: Once you have made the changes to the field properties, save and publish the form.
After making these changes, the Resolution field should no longer be mandatory and will become optional. Keep in mind that modifying the properties of a field in the form editor can have an impact on any associated workflows or business rules, so be sure to test the changes thoroughly before deploying them to a production environment.