There are two ways to do it. It depends what number your transmitter starts with. But I think for all the sensors this method works. It’s really easy to remove the transmitter.
I find the sensors that I restart stay very accurate for me although you still have to calibrate them the first and maybe second day. They can be pretty far off when they first restart for a few hours, so I calibrate them pretty fast and then fine tune it hours or the next day later. Sometimes they stay spot on with the first calibration.
Warning, you only know when they go wonky after they have gone wonky lol, you will start getting some numbers that might not make sense and you check and it’s way off, if you try to calibrate they go off again. This usually happens for me somewhere between 25-35 days. Mine also give me warning by starting to lose the signal a bunch of times one day, then I’ll check it and sure enough it will be off.
This video has the instructions on how to restart G6 sensors that say “No restarts” - I tried it today and it worked! 
Thank you to Type1Tech TipsnTricks!
I’d typed up the steps since the video is long:
- stop sensor on phone & receiver (or wait until session ends)
- use a test strip or thin card to pop transmitter out of old sensor (still in your body) - there is a hidden clip in middle of sensor - try to get it to raise up slightly on both sides and the transmitter will come out.
- wait at least 30 minutes (longer is ok)
- snap transmitter back in old sensor
- on receiver & phone, start new sensor session using original code