Very simple
Goto .htaccess file in your drupa7 folder(ie your project folder. it may in in www/drupal_project/ or public_html/drupal_project/).
.htaccess is a hidden file. So go to this this directory structure www/your_project/(or public_html/your_project/) and press ctrl+h.
You will get all hidden files including .htaccess file.
in .htaccess file, go to line number 106
#RewriteBase /drupal uncomment this line. Replace drupal by your project folder.
If you are not administrator or if you have an account and you working from that account, specify like this, #RewriteBase /~username/your_project_folder
Save the file
Go to admin/config/search/clean-urls this page.
If everything is ok, you will get Enable clean URLs checkbox.
Enable it and now you have clean URL in your site.
Thank you.