If you have an old Seagate external hard drive and you want to pull the disk for some reason, it isn’t very hard to do. Over the last few years we have posted several videos demonstrating how to disassemble Seagate disks.
The things you need to be aware of are that you are voiding your warranty and to not be too afraid to apply some force.
You will need Philips head screwdriver (that is the “star”), and something very thin but strong like a credit card. Typically you have to figure out which pieces of plastic are separate parts and which one are not, then jam the thin plastic card into an opening you pry and slide it around the unit. Then simply use a screw driver to unbolt the drive from any remaining mounts.