my purpose is to remove the title of "Django administration" with yellow color in every admin page like the following screen, please help. thanks.
Copy the default template named base_site.html to your template directory. you can find the default template path by running the command:
python -c "import django,os; print(os.path.join(django.__path__[0], 'contrib/admin/templates/admin/base_site.html'))"
If your template directory named "templates", you should copy base_site.html to templates/admin/base_site.html
Then edit the file and replace {{ site_header|default:_('Django administration') }}
See the document https://docs.djangoproject.com/en/1.11/intro/tutorial07/#customizing-your-project-s-templates