In your main composition, select the precomp layer you want to un-precompose.
Because the original hosting links often break, here is the safe way to get it legally for free. Option 1: GitHub (Open Source) The most modern free fork of the Un-Precompose script lives on GitHub. Search for "aescripts-unprecompose" or "UnPrecompose-master". It is open-source and verified. Un Precompose After Effects Plugin Free Download
Enter the hero of efficient motion designers: . In your main composition, select the precomp layer