You don't cut the tabs off anything! Cutting any metal part will render your wiper arms useless. When I buy a blade replacement, all I get is the rubber blade. I reuse the metal strips and the wiper arm.
You do not need to cut anything (unless you have too long of a blade) to replace a wiper blade. At one end of the rubber wiper blade, the two metal strips embedded on either side of the rubber blade are restrained by the attachment clips of the metal wiper blade arm. This keeps the blade from sliding out. Simply take a pair of pliers and squeeze the two metal strips together at the tip that restrains them in the wiper blade arm. This will allow them to pass through the little tabs on the wiper blade arm. Simultaneously pull the other end of the blade and the rubber blade slides out with the metal strips. Reassemble the new blade with the old strips and reverse the disassembly procedure.