I have never cut Harley's claws as they don't need it (they are walked on pavement for min probably an hour every day, so that does it for me), but with Jess, I only cut the one dew claw as that one grows, and the other one doesn't seem to grow lol.
But yes, to answer your question, it is ok to cut dew claws

Just take it tiny tiny amounts at a time just like the normal nails.