Sometimes when I am learning to use Blender or programming when my mouse goes to the bottom plank pops up.
This is very annoying so I would like a keyboard shortcut to disable it
I'm not sure it's possible to disable plank, but if you install Elementary Tweaks you can move plank to the left or right side of the screen.
Hope this helps.
Actually in 0.4 loki you don't even need Elemenetary Tweaks: you can ctrl + click on Plank and set its position in the Preferences dialog.