OS10# configure terminal 
OS10(config)# port-group ?
  Node/Slot/PortGroup(1-10)  Port-group id

OS10(config)# port-group 1/1/10
OS10(conf-pg-1/1/10)# no mode
OS10(conf-pg-1/1/10)# commit
OS10(conf-pg-1/1/10)# mode Eth 
  100g-1x  Breakout to 1 100G interface
  50g-2x   Breakout to 2 50G interfaces
  40g-1x   Breakout to 1 40G interface
  25g-4x   Breakout to 4 25G interfaces
  10g-4x   Breakout to 4 10G interfaces

OS10(conf-pg-1/1/10)# mode Eth 10g-4x