Renaming

It is possible to rename an existing style.
You cannot rename the 4 master styles.
There are two ways you can rename an existing style:
1) Use the Styles and Formatting task pane.

When you change the name of a style this change is only applicable in the active document.
If you want the name of a style to be changed permanently and to be available in any new document then you must make the change in the corresponding template.

Styles and Formatting task pane.

Select the style
right mouse click, select Modify
In the Modify style dialog box select the style