Like bifold doors, sliding bypass doors are used fairly exclusively for closets. They are lightweight, and may hang from an overhead track or slide on a bottom track; if the latter, there's still an overhead track to guide the tops of the doors. Doors that hang off overhead tracks can be a little difficult to get on and off the tracks, if you've never done it before. Removing the tracks themselves is a matter of unscrewing a few screws.
Removing Doors From Tracks
Whether the doors hang from an overhead track or slide along a bottom track, they are usually separated by a guide that you have to remove.
Remove the guide.
Unscrew the door separation guide from the floor or from the door to which it's attached -- usually the rear door -- by unscrewing it with a Phillips screwdriver.
Take out the front door.
If the doors slide along a bottom track, lift the front door until the bottom clears the track, then angle the bottom toward you to free the the top of the door from the top track.
If the doors slide along a top track, angle the bottom of the front door toward you while you gently lift. When the door is at the proper angle, the roller lifts free of the overhead track. This can be tricky to do, especially if the top track is slightly bent. It the roller gets stuck, free it by moving the bottom of the door back and forth as you lift.
Take out the rear door.
Remove the rear door in the same way that your removed the front one.
Removing the Tracks
The procedure for removing either of the tracks is uncomplicated. Unscrew all the screws you see, using a Phillips screwdriver. If you can't remove the track easily with your hand, use a flat-head screwdriver to gently pry one end away from the jamb or floor. Once you've lifted it an inch or so, the track should come off easily.