Block access to Web Interface

Morning Team.

I was wondering if there is a way to block access to the Web Interface.

We have two Web Interfaces and our Service Desk are using Group 1

We have built two new Web Interfaces on new servers and we have moved some users from Group 1 to Group 2.

However the users in Group 2 can still access old Web Interfaces. Was not sure if there is some simply way to stop them having access?

Thanks in advance