Is there a way to completely disable Spaces in Yosemite?
I did this recently to get an iMac to better support an X-Arcade Tankstick and MAME. I do not know that it totally disabled Spaces, but is has effectively eliminated them for me.

System Preferences &gt; Mission Control: Uncheck everything.
Set shortcut for Mission Control to &quot;-&quot;

System Preferences &gt; Keyboard &gt; Shortcuts &gt; Mission control: Uncheck everything

In a Terminal window enter:
 defaults write com.apple.dock mcx-expose-disabled -bool true&quot;



For more info you can check out:

Managed Client: How to disable Exposé and Spaces

Mac OS X: Disable Mission Control and Spaces