Is there a single user mode or safe mode on a Mac?
If you don't want to load some items that usually start on bootup or login, you can startup your machine in safe mode. From Apple document HT201262:

Follow these steps to start up into safe mode.

Start or restart your Mac.
Immediately after you hear the startup sound, press and hold the Shift key.
Release the Shift key when you see the Apple logo appear on the screen.


If that doesn't prevent your startup items from loading (which it won't if they're kernel extensions), you can boot in single user mode. To do that, hold down ⌘ + s while your machine is booting. You will find your machine boots to a console prompt rather than the graphical interface. Once there, you can move the kext files out the way, etc. Once you're done, type reboot to restart in multi-user mode (and your machine will again boot to the graphical interface). You can find out more about single user mode in  Apple document HT201573.