How to enable/disable VirtualBox's DHCP server.

Goto File -> Preferences -> Network



Now select the VirtualBox Host-only Ethernet adapter and edit it as shown below, then in the DHCP server tab un-check Enable server.


Now press OK twice and you should theoretically be done, but due to a bug in VBox the DHCP is not truly disabled till the time you restart the host machine (The machine on which VBox is running).