This model has what is called a Shepard hook and within the hook there is a small hole that the clip snaps in. Most likely it is a plastic clip, so I take a pliers and carefullty break the clip because they can get seized in place.I have done many of these and that works the best.
Razor blade
Remove the entire skate blade holder - screws and all - from the boot, and replace it with a new skate blade holder with skate blade.
Remove the bolt holding the blade to the left
A paint pen. then remove with a razor blade.
Remove the black cap at base, remove nut, then gently pry up from under the arm this can be a pain but be careful the splines are made to strip to avoid damage to the transmission arms.
Turn the wiper switch to the on position. Turn the key on and as soon as the wipers go straight up then turn them off. That will make it easier to remove the blade. Lift the wiper away from the windshield while pulling down. Be sure to not let the wiper fall against the windshield. Push the new one in place and you are done.
The 2002 Chevy Trailblazer takes 22" replacement windshield wiper blades on both sides front and a 16" rear wiper.
Not sure what you mean by "windshield wiper cover," however if you're asking how to remove the rubber blade from the plastic frame - be careful. The end caps do come off but its not recommended. I recommend simply replacing the entire wiper blade. See videos on link below.
The 2004 Chevy Venture has the most common hook-end arms. See related links below for install video. Press the tab or button which is located where the wiper blade is inserted into the hook and pull the wiper blade out of the hook. You may have to rotate and flex the blade to make enough clearance for the hook to pass through.
Lift wiper assembly off of windshield into "up" position. Rotate 90 degrees. Pull wiper blade assembly gently toward the windshield. It slips right off. Note: Put protective barrier like cardboard or a towel over windshield in case blade assembly snaps back toward windshield to avoid cracking the windshield.
There are several things that you can do to help stop your windshield wipers from squeaking. Clean the wiper blade often to remove dirt and debris. Squirt windshield cleaner fluid on the windows to remove dirt. Ensure that the wiper is screwed in correctly. Replace the blades when it is needed.
It is very simple. In the center of the holder when is pulled out as far as it will go, use a srewdriver blade to push down the tab. The cup holder will now pull out.