How do I uninstall rails for intel se7230nh1lx

I have an intel se7230nh1lx server that has been racked in our server room for many years.  I am trying to uninstall it from the rack but am having difficulty figuring out how to slide the server out from the rails.  Is there a release on the rails somewhere that I am missing?

The rails are manufactured by Schroff and apparently the manufacturing part number is uspt63n127.  Searchs for these rails have come up empty.

Any type of documentation or instruction would be much appreciated.

Thanks very much!!