How should I install laminate without removing the baseboard?
You should remove the baseboard, install the flooring, and then reinstall the baseboard. At least that's how I do it.

Most people leave the baseboard in place, and cover the expansion gap with quarter-round or shoe molding.  If you're going to do it this way, you'll have to leave the manufacturer recommended expansion gap between the flooring and the baseboard. Than as I've said, you'll cover the gap with quarter-round or shoe molding.