I found this support article because I had some invisible members in my vanilla guild on my recovered account, which I could not see in-game, I only found them once the armory updated. However, “/gkick name” did not work for me. I found another post on the EU forums by another player stating that /gremove followed by the first letter of the name will bring up a drop down of member names with that letter to select. That worked for me instead.