To remove an entry, open the child portfolio, then click on the trash button on the right (mobile) or bottom-right (web) of the entry. The entry will be removed from the portfolio, but the entry will not be deleted from the child timeline. Even if it's not in the portfolio anymore, it is potentially still visible to parents if it wasn't marked as private.

Remove entry from the portfolio on the mobile applicationRemove entry from the portfolio on the web application