The most popular and reliable free way to "un-precompose" in After Effects is the Un-PreCompose
Example options and approaches (general guidance)
VideoCopilot Scripts: Often bundled in their free "Motion Design" toolsets, similar layer-management scripts can be found on Andrew Kramer’s site. How to Use It Select your Pre-comp in the After Effects timeline.
The Unprecompose plugin boasts an impressive array of features, including:
.jsx or .jsxbin file.Scripts.File > Scripts > [Your Unprecompose Script].You know the workflow. You’re working in After Effects. You have a complex sequence with masks, keyframes, and effects. To clean up your timeline, you hit Pre-compose (or Shuffle in some NLEs).
does exactly what Adobe should have included years ago: it extracts all layers back into your parent composition while keeping your effects, keyframes, and expressions perfectly intact.