AFAIK, if you have standalone animations, you have to call stop() on each one of them.
If you have grouped them into say a single Parallel or Sequential animation (based on your requirement), then you can just call stop() on this animation.
Depending on the circumstance, you might also be able to bind the running property of each animation to the same property (e.g. property bool animationsEnabled). Stopping all the animations is then just a matter of setting that property to false.