It's possible to disable SIP by booting to Recovery HD and running the following command:
csrutil disable

It is also possible to enable SIP protections and selectively disable aspects of it, by adding one or more flags to the csrutil enable
command. All require being booted from Recovery in order to set them:
Enable SIP and allow installation of unsigned kernel extensions
csrutil enable --without kext

Enable SIP and disable filesystem protections
csrutil enable --without fs

Enable SIP and disable debugging restrictions
csrutil enable --without debug

Enable SIP and disable DTrace restrictions
csrutil enable --without dtrace

Enable SIP and disable restrictions on writing to NVRAM
csrutil enable --without nvram

I also have a post available with more information about SIP:
System Integrity Protection – Adding another layer to Apple’s security model