same way you turn it on actually. in the graph editor to turn off showing of infinity choose view -> infinity (its a a toggle).
However if you mean how to turn of the infinity of the curves animation, then you cant! you can just chose form :
- Cycle
- Cycle with offset
- Oscillate
- Linear
- Constant
The reason for this is clear maya cant just go out and stop sending a value (theres no such thing as a valueless number), however the reason i highlighted constant is that tjhats what most consider NO INFINITY. Its is still a infinity of sorts, if you realy thinkabout it.