Epson EB 824 - Manual (Page 81)

Removing USB Devices
After finishing projecting, follow the procedure below to remove USB
devices from the projector.
Procedure
Remove the optional Document Camera from the projector's USB
Port (TypeA).
For digital cameras, hard disks, and so on, turn off the power to the
device and then remove.
Connecting and Removing USB Devices (EB-826W/825/824/85 only)
81