Is 5 years old too young to be grounded?

My S/O and I are completely different parents. He coddles our boy. There’s not much discipline on his end. If our kid demands, he gets. Today our kid kicked the closet door off of the hinges and I told my S/O he has to be grounded, my S/O was completely taken aback, he thinks he’s too young for everything. I could barely get him to stop co sleeping just recently.... Bedtime is 2 hours long if I let it be, because my S/O thinks he has to talk or pet a 5 year old to sleep.... Our kid constantly tells us no, shut up, he hits, he spits, he jumps, he kicks... My S/O thinks our kid runs the house as well as our relationship and Im at an end with it. Am I wrong for wanting to ground our 5 year old? Strip him off his toys, TV, and outside for 3 days? I think thats starting off light.