Happy National Bike Day

>unseize a seat post

The first thing you need to do is determine why it’s stuck, whether the cause is mechanical or corrosion, a.k.a. rust. From the look of that chain, I’d guess that post is rusted in there. Ugh! That chain is crusty!

But anyway, I’ve never had to remove one so here’s what I would do. First, I’d remove the bottle cage and screws. With the bike turned upside down, I’d blast some WD-40 in one of the holes on the seat tube. Let it sit overnight. Next day, try to turn it with your saddle attached. If that doesn’t work, I’d consult Sheldon Brown… So, here ya go: [Sheldon’s Seized Seat Post Removal Tips](https://sheldonbrown.com/stuck-seatposts.html).