1. A pull down is called an 'Option Set' in CRM. In the Solution Customization open Opportunity fields, Click New and choose the Type as 'Option Set'. This will allow you to add values to the list and also set a default. Once you are done adding the values
and saved the field, publish the customizations.
2. You cannot remove the Topic field from Opportunity as it is the primary field and is locked on the form. Alternatively, you can hide it by un-checking the 'visible by default' property (open the opportunity form and change the Topic's properties). Change
the Field Requirement to be 'Optional' (Navigate to Solution Customizations -> Opportunity -> Fields and open the Topic field). Set a default value for topic using a Form script as the topic field is shown in the opportunity form's title.
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