Deleting aspects of Ancestry?

I may just be missing it but when trying to use the “cog” in the lower part of character sheet to update stuff I don’t see any way to combine ancestaries, but I selected the no limits option when creating to make a Half-Elf, but now I want to pick 2 of the 4 abilities that would come with that, instead of just having Human on my sheet? Is there a way to do this?

In the Ancestry section of the character builder you should see Mixed Ancestry at the very top. If you select that it will allow you to pick the top/bottom aspects of the two ancestries that you want to mix.