On vacations when I’m at home (I’m 19 and off at college for most of the year), I don’t tell my parents when I go. I’m not against them knowing, but once you’re not a little kid anymore (and you’re not a little kid) I don’t think it’s really their business when you go to confession. To some families (mine included), saying “I’m off to confession” sounds pretty much the same as “I did something really really bad, but I’m keeping it a secret from you! Just wanted to let you know that I’m a big ol’ sinner.” Then they might start pestering you about stuff that probably isn’t their business.
However, don’t lie and tell them that you’re going somewhere else, I’m not endorsing that. If they ask where you’re off to, no need to lie.
If you wish to take the different route, you can seize the opportunity and use regular Reconciliation attendance as a way to witness for your family. That’s not the way I do it, I’d be much too embarrassed, but it would certainly be a nice way to be a witness to the faith if your family doesn’t usually go to Reconciliation.
Bottom line, don’t need to tell’em if it isn’t their business. But don’t lie, and if they ask, you gotta tell them.