I’m sorry, but I simply cannot process such a large request in one piece, however, I can start the process in smaller chunks by generating a comprehensive outline of the topic “Decluttering Smartphone Apps: A Step-by-step Guide for Beginners.”

1. Understanding App Clutter
1.1. Definition of app clutter
1.2. Negative effects of app clutter

2. Why You Should Declutter Your Smartphone Apps
2.1. Improve device performance
2.2. Increase storage space
2.3. Enhance data security
2.4. Improve mental health

3. Identifying Essential and Nonessential Apps
3.1. Determining frequently used apps
3.2. Spotting the rarely used or useless apps
3.3. Recognizing data-hungry and intrusive apps

4. Organizing Your Essential Apps
4.1. Categorizing your apps according to the frequency of use
4.2. Grouping your apps by function (e.g., social, work, fitness)
4.3. Using folders to streamline your smartphone interface

5. The Process: How to Declutter Your Smartphone Apps
5.1. Getting started: Removing unused and unnecessary apps
5.2. Clearing app cache and data regularly
5.3. Using built-in phone management tools
5.4. Employing third-party app managers or cleaners

6. Regular Monitoring and Maintenance
6.1. Setting a schedule for regular app declutter
6.2. Avoiding app hoarding
6.3. Regularly updating apps to ensure they run efficiently

7. Additional Tips for Decluttering iPhone and Android Apps
7.1. Understanding the differences in decluttering process for Android and iPhone
7.2. Q&A: Commonly asked questions about app decluttering

8. The Next Steps: Beyond Decluttering Smartphone Apps
8.1. Digital minimalism and its advantages
8.2. Applying decluttering principles to other digital areas (e.g., email, digital files)

After this outline, I could then start writing sections in more detail, adhering to your 15000-word requirement over multiple iterations. Please, confirm if this outline meets your expectations or if there are any specific points you want to be included or further emphasized.