You are getting the message because those fields are mandatory. If you want to hide, set the pre-defined value for them.
Set Predefined Field Values for Quick Action Fields
When you create actions, use predefined field values to set a value for a field. Predefined values can help ensure consistency and make it faster and easier for users to create records.
If you set predefined values for fields on object records created
through an action, you don’t need to add those fields to the action
For example, when you configure an action that lets users create opportunities, set Prospecting as the predefined value for the Stage field. All new opportunities users create through that action are automatically assigned to the prospecting stage. You can remove the Stage field from the action’s layout, because the field is going to be assigned a value automatically.
Predefined values for fields on actions are different from default
values that you can set for fields on records. If a field is included
in an action, it can have both a predefined value set for the action
and a default value set.
Steps to follow:-
- Click the name of an action in the Buttons, Links, and Actions list
or the Global Actions list.
- On the action detail page, click New in the Predefined Field Values
list. Select the field you want to predefine a value for.
- Specify the value for the field.
- For single-select picklists, you can specify both a specific value
and a formula value. If you set both, the formula value takes
precedence over the specific value.
- Click Save.
On object-specific actions, the predefined value can include
references to the source object and its related objects.
You would like to see:- Notes on Predefined Field Values for Quick Actions
Reference:- Set Predefined Field Values for Quick Action Fields