If it's because of the money, please be aware that replacing the crankset is a silly use of money in the first place. If you don't use the 30, then don't use the 30. Put your money in the bank.
I agree. And if the issue is that you don't want to accidently shift onto the small chainring, I assume that you could set up the derailleur and shifter as if it were a double, just like you'd have to if you changed the crank. Frankly, I'd leave it as it is. I "never" use my granny ring on my triple. That is until I was in the middle of a ride I'd never done before and hit 4 very steep hills in succession that inspired me to use it. I might not have made it home without granny's help. I even passed a couple of much stronger riders struggling up the hills with their lowest gear on their doubles.