Hello, as others have said there are no "back-in-the-day" internal upgrades to the A500 that store personal information. I shot a couple phone videos to help explain things. If you had a hard drive, it would be an external box that plugs in here
As for the battery Mr. Intric8 mentioned, that is located here.
Please note I am pulling the circuit board horizontally to remove it.
I know you said you do not want to keep the computer, but a working Amiga will fetch a higher price than an untested one. If the machine was not tightly wrapped up and has dirt or dust on it, check inside before you power it up. This person's video was my reference
for how to get inside and inspect. I'm waiting on parts to get my Amiga to boot before I take the time to make it pretty so i went out-of-sequence from what he did.
Regarding floppies, take them on a case-by-case basis. Games won't have your personal info so you don't need to check those discs. In case you forgot, WORKBENCH is the boot disk. The A500 will likely ask for it when powered on.
When you first attempt to power up, do not connect the hard drive or external floppy, Just use the power supply, monitor, and mouse. The machine should ask for a Workbench disk.
Put that floppy in the internal drive and pray. After about a minute of coffee grinder noises, you should see the old familiar screen. Move the mouse around and click things to make sure the mouse works.
Power down, eject the Workbench disc and connect the external floppy drive if you had one. Power on again and there should be an additional icon once you get to the Workbench screen. Stick a disc in there and see if it reads.
Power down, eject the Workbench disc and plug in the hard drive if you had one. Power on again and see if the computer goes to Workbench without asking for a floppy. Regardless of whether the Amiga boots from your hard drive, there should be an icon for the hard drive when you get to Workbench. Click it and see what old documents are still there. Click-and-drag the desired documents to the Trash Can. Then go up to the menu bar at the top of the screen and "Empty Trash".
Job done. Your personal files are gone. If you want to clean up the exterior a bit, refer back to the RetroManCave video I shared.