I've been first responder to 2 dryer fires. I've caused 2 completely seperate dryer fires. Its impressive how fast it travels. I've cleaned several hundred dryer vents. I've also hired out several hundred to vendors.

You can buy a kit from lowes. Using a shop vac with the included adapter helps.

If it hasn't been done in a while you can scrub with the sticks while the dryer is on but dont go farther than 1 sticks worth at a time before pulling the brush out and letting it clear itself. Then add a stick and scrub in ward.

This will only work up until a 90 fitting. Most kits and even every pro I've worked with will pop a 90 fitting apart inside the wall and then you will have to cut the wall open.

Shoving the whole stick in will result in pushing the lint into a blockage. On a two part run that has a 90 in the middle I always do the outside first. Scrubbing the stick in and out then move up another foot on the stick and repeat. They're a yard long so every stick withdraw it completely and let the big clump you pushed forward clear. From the inside do the same thing but use an electric leaf blower with the shopvac adapter on the exterior. If you do the inside run first it will probably clog up. You can get around a 90 if you can reach it to bend the stick around it by hand