I know there are several different types of drawer removal mechanisms. (Not sure on the names so feel free to edit)
These open by simply rolling the drawer fully out and lifting the wheels on the back of the drawer up off the track and then pulling them out.
These drawers can be removed by rolling the drawer fully out and lifting the two levers on the inside of the track. A YouTube video clearly shows this.
In track, no levers.
No clue how to open this.