Tips say you can stop nunu ult prematurely but pressing it again doesnt work how do u
 

The ingame tips say you can stop nunu ultimate Absolute Zero prematurely but pressing R again doesn't do it. So how do you stop it?

Right click somewhere to make him move?

ok, for some reason didn't occur to me. thanks

This, or ask someone on the enemy team to CC/kill you.

You can also cast another spell or abilty, like ice shot or blood boil.

Ask the enemy ziggs to use satchel charge

give nunu any other command to set his ult go off early, like move, attack, or use other spell