What is the proper way to reset a modem/router 2-in-one device?

So I own my own modem/router combo. I only need the one device, no longer need a router. My problem is when I go to reset the modem/router, typically I unplug it from the wall and let it sit for 2 to 5 minutes. I hear that unplugging it is not the exact right way to accomplish the task.

So I wanted to ask here if there is a certain way I'm supposed to be resetting it?

Thanks.