Newer homes have an external service disconnect...if yours does, unplug the connection and the internal wiring would certainly be disconnected.
The line probably does not have any power on it, but it's not that hard to test if you have a multimeter. But, in case the house is ever sold, if I cut it, I'd want to ensure that the wires weren't shorted to each other which would make re-establishing service much harder to do without lots of diagnostics. FWIW, the voltage isn't all that high unless there's a ring voltage occuring. That, if you contact it, will get your attention.