Calm corner

I have a 5, 3 and 6 month old. My 5 and 3 yr old will not stay in the calm corner when they go out of instructional control or don't accept a no etc… of I hold gently thrill will bite, lock, hit and try to get out and make it game or call help me over and over again. They will say their ready to be calm but when I get up and leave and walk away they laugh and will run away (this is when just one person is in the calm down corner.

If I don't hold them it will turn into a one way game of tag.

What do I do to get my little kids to stay in the corner thanks!