how do i reset roku tv properly?

if the reason you're resetting is the remote stopped working, get the roku app on your phone first. same wifi as the tv and it works as a remote, so you can actually get into the menus to do the reset. saves hunting for the pinhole.

Depends what you mean by properly. If it's just acting slow or freezing, Settings > System > Power > System restart fixes most of it and you lose nothing. For a full wipe it's Settings > System > Advanced system settings > Factory reset. It asks for a code shown on screen, then reboots into the setup wizard. If the menus won't load at all, there's a small reset button (or pinhole) on the back or underside of the TV. Hold it in with the TV on for about 10-15 seconds until the light blinks. The bit people forget: after a factory reset you have to sign back into your Roku account and every streaming app, so have those passwords handy before you start.