Slide the tray from the seat by pushing the handles underneath into the tray while pulling the tray toward your body.
Remove the straps from the seat. Each strap has a separate tab at the back of the seat. Squeeze the tab and pull on the strap from the front to remove. Repeat with each strap. Remove the seat pad if you have one.
Lay your chair on its side and locate the two screws holding the cover for the seat base into place.
Select the appropriate screwdriver (cross or flat-headed) and remove the screws, allowing the cover to slide down the support tube.
Unscrew the seat from the seat base.
Go to the highchair base and locate the gray circular area or "disk" underneath and the two plastic tabs in the center that hold the disk to the base.
Unlatch the disk from the bottom of the base by pushing one tab toward the other with a flat-headed screwdriver while pulling on the disk.
Look for a metal tab in the center area revealed with the removal of the gray disk.
Separate the highchair base from the support tube by placing the head of a flat-headed screwdriver under this tab and applying upward pressure to the tab while firmly grasping and pulling the support tube away from the base.