Quoting boobook:" Is 5 years old too young to ground from TV for a day? Or is he still too young? Thanks!"
Heck no!! I have been taking privledges from my girls since they were 3. As soon as they understand it is a go! Just don't take away anything that they can't ever earn back. For example, don't take away a birthday party they are supposed to go to. It doesn't send the proper message. You want them to learn from the error and correct it to earn back their privledge.