How to remove dropdown menu arrow

Hi everyone,

I am running the pho theme and trying to remove the little downwards arrow that appears next to one of my drop down menu. You may see what I’m talking about here: https://thais-breton.com
I tried this code in my Custom CSS which I found on another similar thread, but it didn’t work for me!
#header-menu > li.menu-item-ancestor > a {
background: none;
}
#header-menu > li.menu-item-ancestor > a {
background: none;
padding-left: 0px;
}

Thank you kindly in advance for your help.