Highlight your final composition, then from the Menu Bar(PC, not sure the Apple equivalent), go to File/Dependencies/Remove Unused Footage. This will get rid of anything that is not associated with the Final Comp. All precomps and precomps in precomps that contain assets will be fine.
Word of advice, save before you do this. Then do an incremental save after…just in case. Also, if see that too much has been deleted, you can cntl+z to undo the Remove Footage action.
Johnny Cuevas, Editor
ThinkCK
“I have not failed 700 times. I have succeeded in proving that those 700 ways will not work. When I have eliminated the ways that will not work, I will find the way that will work.”
—THOMAS EDISON on inventing the light bulb.