Ok now you have to promise not to hold me accountable if you are a klutz & hurt yourself.
Here’s the drill:
Approach the bike from behind, kneel down upright, reach out.
In your hand you have a skill-saw.
One end is sharp & spinning. Do not interface with soft fluid filled parts.
Use one of those spring sash clamps to hold the safety guard out of the way, this immediately sounds unsafe, but means you can use two hands on the handles.
Rub the blade on the rounded leading edge of the knobblies. You just need to cut a couple of mm away, but you aren’t cutting down, you are using it like a grinder. As long as middle row have sharp edges. Stop, wait till spinning stops & rotate the tire, continue.
Do in well light & ventilated place, throws rubber shards. Wear hearing & eye protection.
Think about what happens if you slip, which is why I suggest to kneel upright & why I don’t put the bike on a stand. Take breaks if arms get sore as you are reaching out.