I have always just had a "last mow of the year", where when I run the mower dry, and I've never had a problem. Then you're not really "wasting" the gas.
Depending on your model (and it looks like the one you specified ought to manage this), you may be able to do option 2 if you have a really full gas tank. Then, after emptying, you still ought to run it dry for what little remains.
I personally would not recommend siphoning it. Unless you wanted to go to the trouble of buying extra equipment to do it (and think about that - how often are you going to be siphoning gasoline? Enough to justify a special purchase?), that means a distinct risk of drinking a little bit of gasoline... not exactly a pleasant experience, nor good for you.
from this site:
Many adverse health effects of gasoline are due to individual chemicals in gasoline, mainly BTEX, that are present in small amounts. Breathing small amounts of gasoline vapors can lead to nose and throat irritation, headaches, dizziness, nausea, vomiting, confusion and breathing difficulties. Symptoms from swallowing small amounts of gasoline include mouth, throat and stomach irritation, nausea, vomiting, dizziness and headaches. Some effects of skin contact with gasoline include rashes, redness and swelling. Being exposed to large amounts of gasoline can lead to coma or death.
So, siphoning probably won't kill you, but I certainly wouldn't endorse it.
Contractors at construction sites often place their valuable gear out of reach of potential theives.
![enter image description here](https://i.stack.imgur.com/pgAqo.jpg)
Now expecting that this approach may not be practical in your particular case the next best advice is "out of sight is less tempting". Wheel your gear into a shed or garage and lock it up.
Best Answer
1 cup (5% laundry) bleach to 1 gallon water is usually a good bet to kill most things. Use in a well ventilated area, and never mix ammonia and bleach. (Which you all should know already, but evidently some people still don't...)
With a lawnmower, getting the blade and underside clean enough to paint (remove all grass clippings - and hey, if you've gone that far, why not paint it!) will help immensely in not having residual clumps of stuff that might not have gotten bleached all the way through. Clean (but don't paint) the wheels/tires (if any) as well (evidently hover mowers are still out there, wheel-free.)
"Red Thread" seems to be a more common name (I get no results for "red thatch" other than "red thread" and "pink patch" results.) Both are fungal diseases. A bleach solution will kill fungus on non-porous surfaces (such as your mower's steel and plastic) but is less effective on porous surfaces (which would mostly be the "age of the mower old" buildup of impacted grass clippings, in lawnmowers.)
Sharpening the blade is also a good idea for prevention, as these diseases more easily attack damaged grass blades than ones that have been cut cleanly.