Select REGISTER/LOGIN in the main menu, then Forgot password?
You should receive an email within a few minutes with a link to set a new one.
If it does not arrive, check your junk or spam folder, since password reset emails are often filtered there. If it is not in either, the most likely explanation is that the address you entered is not the one your account was created with. Try any other address you might have used, including a work address or one you have since stopped using.
If you signed up with Facebook or Google rather than an email and password, there is no Race Space password to reset. Use the same Facebook or Google button you originally signed up with.