Depending on the brand and drawer slide.
There’s a latch on the inside of the file cabinet. On the rail part.
Usually just pull out the drawer and lift up.
Sometimes the drawers can be extra stubborn to remove even by releasing the latches, if the rails are bent, or if the drawers are warped.
To avoid cutting your fingers, as the rails can be very sharp, It is best to wear gloves if possible, and have one person hold the cabinet, and another person try to remove the drawers.