It's easy to wash in the bathtub. It's a good skill for when you travel and don't have a washing machine at your hotel.
1. Bathtub stopper in
2. Put detergent in bathtub
3. Fill bathtub with water (temperature depends on how you normally wash it)
4. Put gi in bathtub
5. Use a plunger to agitate it, walk on it, use your hands, etc.
6. Drain the water
7. Fill tub up again with clean water
8. Plunge, walk, hands, etc.
9. Drain the water
10. Fill tub up again with clean water
11. Plunge, walk, hands, etc.
12. Drain the water
13. Squeeze water out of your gi
14. Hang to dry