how to discover where mini-panels are surfaced in Drupal 7
Assuming your site is using Drupal 7 version.

Mini-panels gives us a way to group together multiple blocks (and other content) into a single block. Which can then be placed on page using Panels or Drupal Blocks (Admin => Structure => Blocks). Check this Question Looking for a good Mini - Panels tutorial for more details.

There are 3 places you can check if Mini Panels are actually used in your site:


Drupal Blocks (Admin => Structure => Blocks) - Block name is usually shown as 'Mini panel: "Mini Panel Name"'
Panel Pages (Admin => Structure => Pages). Check all panel pages by editing them and navigating to Content section of Panel page.
Rendered in Code directly (Since this works similar to block, and can be rendered using the way blocks are rendered programatically). i.e. programatically rendered in theme or module. This might not be in your case, but just to make sure you can check this as well.


This Tutorial shows use of Mini Panels as Drupal Block.

Check out this tutorial on How to use Mini-Panels to create one block that includes all our global blocks - The video is paid, but description gives an overview of what it is.