Hi,
I can understand how this may appear confusing. In actuality, the 'x' function on the UI attempts to disconnect the client when it is used. However, for most wireless clients, they will automatically try to reconnect to the network. If the network policy is such that they are still allowed to connect, then it would appear as if nothing happened. If the new network policy is such that they are still allowed to associate (i.e., not blacklisted) but not allowed to authenticate, then it would appear that the client is still visible in the UI but its state would reflect a state of an unauthenticated client (its role would be pre-auth role, or it would fail to get an IP address). If the new network policy is that the client is blacklitsed, then they would not be able to associate at all and it should disappear from the client list.
Thanks,
Yan