MY iphone is disabled and I can't turn it off

I forgot my pass code number and my phone was disabled. I connected to Itunes and followed the instructions. My phone's software was updated by Itunes. I got the Apple logo then it went back to "Iphone is disabled" Connect to Itunes" screen. the phone will not turn off in order to repeat the procedure no matter how long I kept pressing the side button [it's an Iphone 6 plus]. How do I turn it off or is there another way to access my phone again.