What actions should be taken prior to converting the relationship?

Delete all roll-up summaries that reference the detail object prior to converting,

Feedback: https://trailhead.salesforce.com/en/data_modeling/object_relationships You can change the parent record for a child record in a master-detail relationship. To enable this option, select the Allow reparenting option in the master-detail relationship field definition. By default, you cannot reparent records in master-detail relationship. Converting Relationships You can convert a master-detail relationship to a lookup relationship as long as no roll-up summary fields exist on the master object. https://help.salesforce.com/articleView?id=relationships_considerations.htm&language=en_US&type=0