There is a field in gameplay interface that pastes that green thing there when it's in use. If you remove that, you don't see it in the game. Find it yourself.
But I fail to see why is it important o.o
"Channel" It's a Hero abilit by default.
You also should check Options - Visible to true, Disables other Abilities false, and make it instant (no target).
And look up some Channel tutorials (use search)
Ghan has said he has fixed this. Monovertex please confirm this fix. This was only a problem with people that had signatures in the upper levels like not the special members but the respected members.