Please take backup of your customization before you try this. Here is a step by step guide to remove a system locked section.
1. Export Service Appointment entity.[Take a backup of the zip file you just exported].
2. Extract content of the zip file -> customization.xml.
3. Open the xml in your favourite xml editor. You can use Notepad or Visual Studio to keep it simple.
4. locate the following section “scheduling information”
<section name=”scheduling information” showlabel=”true” showbar=”true” locklevel=”1″ id=”<GUID>” IsUserDefined=”0″ layout=”varwidth” columns=”11″>change locklevel 1 to 0.
5. Once you have done it, import the customization back to CRM.
6. Open the Form.
7. Move Start Time and End Time to a choice of your section. You can Duration and All Day Event as well.
8. Remove the section.
9. Preview and Test.
In case things do not work as expected, use the backup and restore the entity.