Grab your lubricant, I also have a degreaser. And any cleaner with citric would be amazing for your bearing.
I would get some water.
Flip your longboard so the wheels are facing up.
Grab a tool that fits onto the screw holding the bearings.
As you can see here.
Grab your tool and screw it off. Lefty loosey righty tighty.
Here it comes off.
These two things may come off too.
Set them on your board for later.
Here is my wheel and bearing.
Wipe off any visible grease or muck on the bearing.
Wipe inside the wheel with a paper towl.
Wipe off any extra lube.
It should look pretty clean.
Now you're done! Go out and have some fun.
This is how long it spun before!
This is after! Wow!
The creator of this guide has not included tools