This video shows you how to remove the rear tire, tire tubes, and replace a flat tire tube.
It also shows you how to prevent flat tires and stop flats.

NOTE Due to multiple questions about this. KEEP THE OLD TUBE CAP AND USE THAT ONE ON THE NEW TUBES.
It's shorter than the one they give you with the new tubes and won't hit the frame.

FVRITO 10x2.50/2.75 10 Inch Inner Tube for Smart Self Balance mobility Electric Scooter 36v 48v 400w 500w 800w Hub Motor Mijia M365 With TR87 Angled Stem 2 Pack https://a.co/d/6JA04GA

BW Bike Tire Liners – Inner Tube Flat Protectors for Road, MTB and BMX Bicycles 12”, 16”, 18”, 20”, 24”, 26”, 27.5”, 29” and 700c https://a.co/d/12B3LIZ