Reasonably simple, but you need to be at level 10 in Pyramid to be able to apply the Pyramid card back to your deck.
When you have reached level 10 in Pyramid start up any game of TriPeaks (obviously easy 1 board would be the quickest) and click the palette with paint brush icon called Cards and scroll down to the Pyramid one.
Once you have it applied continue to clear the board and the achievement should pop when you go back to the home screen