public Section removeSection(String sectionName) {
        String name = cleanName(sectionName);
        return this.sections.remove(name);
    }
Removes the section with the specified name and returns it, or {@code null} if the section did not exist.

@param sectionName the name of the section to remove.
@return the section with the specified name or {@code null} if the section did not exist.
config/core/src/main/java/org/apache/shiro/config/Ini.java