It’s rather easy, when your SoC is under 85% and speed is over 20 kmph, turn the throttle in the reverse direction. It doesn’t have much play in the reverse direction but a little bit of turn does the job, it reduces speed slowly till about 20 kmph and then you’ll have to use brakes. Also, according to an FAQ I read recently by @rajeshkav it doesn’t really regenerate too much energy but if you ask me does a decent job of slowing you down in moderate traffic. Also, just a safety reminder don’t use this for emergency braking, the brake lights don’t turn on when you use regen and it isn’t strong enough for emergency situations.
On another note, I usually average between 27 Wh/km and 30 Wh/km. Hilly terrain and climbing flyovers really doesn’t help much with efficiency unfortunately.