How setup empty Portfolio slug in Avada

Hi everyone!

Please help me to setup empty Portfolio slug in Avada. Now i have next link to portfolio post -

I want delete avada_portfolio/ from that address. I see in setup Avada one possilibity - delete any symbols from Portfolio slug - but actually i have default record for slug - avada_portfolio. I am spent lot time for find solution to this problem but any not work for my wordpress.

Now i am using multisite wordpress 4.6.1 version.

Thank you in advance!