1) Save a backup copy of your AEP file — just in case.
2) Select the composition you want to keep in the project panel.
3) File > Dependencies > Reduce Project. Ae will remove everything from the project except for the comp you’ve selected, and any other project items it requires (assets, nulls, solids, precomps and everything nested within them).
4) Save AS (so you don’t overwrite your original).
You can also use Collect Files afterwards to copy all referenced files to one single place for easy transfer, or you can use Collect Files in place of Reduce Project in step 3 (it also has a Reduce Project option).
Walter Soyka
Designer & Mad Scientist at Keen Live [link]
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
@keenlive | RenderBreak [blog] | Profile [LinkedIn]