close down
With or without an object
Stop operating for good (a business)
The factory closed down in 2009.
With or without an object
It can be used with no object, and it can also take one. With an object it is usually separable: turn the volume up, turn it up.
The particle: down
This verb belongs to the group ‘breaking and closing’.
Others in the group: break down, shut down.
Practise it
Add it to your daily practice or see every verb with down.
Further reading: close down on Wiktionary (CC BY-SA).