how to delete extra import data from import without loosing used data?

I want to use the adjustment layer from my project 1 to use in project 2. 

In project 2 I import the composition with the adjustment layer. Then I copy the adjustment layer where needed. 

When I now delete the imported composition, the copied layer also disappears? Have also tried with duplicate instead of copy, same result. Is there a way to use only the layer and have the imported composition (with the original layer) deleted?