It is simple to prevent the coin from finding PoS blocks.

In your $HOME, open .cachecoin/cachecoin.conf in a text editor

Add a line to it and save it:

reservebalance=999999999

And then if cachecoind was running, restart it.

Reserve balance is amount of coin that are to be ready and will NOT take part of staking.
Setting it to anything larger than your balance will effectively turn off the staking.