How do I remove A WIFI account which I no longer use>

What do you mean by "WiFI account". If you want to forget the network, tap the ℹ next to the network and tap "Forget this network".

If you mean prevent it from showing up on the list of available networks, you can't. If you mean prevent the device from automatically connecting: Settings app > Wi-Fi > [tap the ℹ icon] >Forget this network. You will need to be in range of the network to do this (otherwise it will not show up on the list).