How to Rewire Powered Switch Controlling Half Hot Switched Outlet to Power Outlet as Always On and Control/Power Recessed Lighting
Simply cap off the red wire at the receptacle and the switch, using a twist-on wire connector. Then replace the receptacle with a new one, that doesn't have the tab broken between the ungrounded (hot) terminals. On the new receptacle, connect only the black, white, and ground wires.

Now the receptacle will always be hot, and the switch will be unused. This will allow you to use the switch for your new lights instead. Just connect the black wire going to your lights to the switch, and the white to the other white wires in the box.