Hmm.. If it is under warranty, then I would contact the manufacturer about fixing it.
However, if it isn't under warranty, then you have the option of opening it up to try to fix it yourself, or taking it to a local tech.
Should you choose to try to do it yourself, be careful. It will need first to be cleared out of dust, debris, etc. From the fans to the vents and everything else inside. Should that not resolve it, then you will need to change the thermal paste.
Just be sure you can do the work, it is really easy to open up a laptop and cause more damage than you started with.