You can get what you asked for (in the second half of your question) from your signal like this:
newSignal = signal(10:10:end);
Of course subsampling a signal speeds it up becausethe time is now shorter, if you're using the same time scale. Instead of a sound playing in (say) 100 seconds, it will now play the complete sound in only 10 seconds - ten times faster than before. To make a signal be 1 Hz instead of 10 Hz on the same time scale you need to stretch things out - add samples, not get rid of them.