You can hide "Join" menu item and set in admin panel->Global Privacy option "Who can join" to "By invitation only". So, if somebody will type in browser yoursite.com/join , system will not allow to register

thanks, but what I need to be able to do is have a single registration.

What do you mean under single registration? :)

where an individual that signs up only has to do it once. Since there are two programs that I want use together and they both require user sign up. I want only
one sign in for both.

yah how about that?

It should be a custom integration oxwall registration process into your other system. In your system, you need to find out a aprt of code, which register new user and add here some sql queries to insert registered user's data into oxwall's database

you can contact Connect Business Centers if you want to know about Ejari registration centers in Dubai.