I've written an AMX plugin to add and remove bots via a simple GUI. You can download it at my
website. This is link directs you to version 0.1. There is also a version 0.4 which has a enhanced GUI and an autofill function but is broken in some ways.
If you search this forum you should find "realbot_simple" which is 0.4 without the broken autofill funktion.
Or if you have some programming skills you could pick my joebot_control plugin - which has all the bugs in 0.4 fixed - and backport it to realbot

.