Whether you "ripple" or not isn't an explicit setting in the client, nor should it be. Rippling happens when you extend trust to more than one issuer for the same type of currency. If you don't want to "ripple", don't extent trust twice for the same currency.

I opened an bug issue asking for an explicit warning in the client when you extend trust the second time:

https://github.com/rippleFoundation/ripple-client/issues/682