How do I get rid of P0420 Code for honda accord 2010?

I have had a check engine light for a few days now and when i plugged in a code reader, P0420 came up and i looked up how much it would cost to fix it and it is over a thousand dollars (money i do not have). I looked up a video on youtube by scotty kilmer and he said to put 1 gallon of lacquer thinner in the gas tank when it is half full and drive it at high speeds to clean it. Will this fix my cars problem? I do not want to replace the catalytic converter so what would happen if i ignore the light?

$1000.Wow
An after market converter is $40 - $60
2 clamps $6.

Look on Craigslist for a 'mechanic'.

The problem might be a air leak into the exhaust system. The "front pipe" on these cars often blows out (it is a flex coupling).
They are not cheap, they do bolt in. A lot cheaper then the convertor.
NO your proposed solution will not fix the problem.

Lookit

You're leaving out important information. The OBDII will tell you which sensor is "bad". I don't see where you indicated which sensor it is. You also didn't tell us whether your car is a 4 or 6-cyl. This will make a difference in the number of sensors your car has.

A gallon of lacquer thinner in your tank would not be good at all for some of your fuel system components. I'm not familiar with the chemistry but rubber lines, regulator diaphragm, and injectors could be susceptible.
If you want to clean it have it removed and filled with solvent overnight and then blown out, re-installed. It works very well. This also gives you a chance to see if the substrate is even intact and capable of being useful anymore.

The lacquer thinner won't work. That's been proven over and over again and can absolutely damage the fuel system. Several car makers have issued service bulletins warning not to try this. Scotty also recommends washing the cat convert in Dawn dish washing liquid what has also been proven worthless. Stop watching Scotty. If you ignore the light, you'll lose more and more performance until the converter is completely plugged up, at which point you'll have to replace it. When it comes to that you'll either have to pay the money and replace the cat or junk the car. Welcome to car ownership.

Stop assuming you have to replace the cat. That's what idiots do.

Leaded fuel was used where unleaded was called for (unlikely)
A damaged or failed oxygen / O2 sensor Downstream oxygen sensor (HO2S)
wiring damaged or connected improperly
The engine coolant temperature sensor is not working properly
Damaged or leaking exhaust manifold / catalytic converter / muffler / exhaust pipe
]Failed or underperforming catalytic converter (likely)
Retarded spark timing
The oxygen sensors in front and behind the converter are reporting too similar of readings
Leaking fuel injector or high fuel pressure
Cylinder misfire
Oil contamination

Read more at:
Copyright OBD-Codes.com

The CEL with the P0420 code is one of the few codes that directly points to a bad catalytic converter which needs replacing. Advance Auto sells Walker brand converters which work.
Driving as it is will not damage anything as long as your motor doesn't have any other issues causing it to run poorly.
Drive at higher rpm's to heat the converter hotter to see if it clears up. I've had a P0420 code set when idling for a long period of time in traffic. I turned the light out and drove the motor at higher rpm's and it hasn't come back on yet.
It is the converter and not 02 sensors. Because the code set it means the 02 sensors are all working.

The catalytic converter on my old Ford Ranger pickup split open several months ago. It was cold, sloppy snowy winter. I'm retired and sold my business last year, so I'd have to lay on the cold garage floor, just like many DIY people here do. I didn't want an under-the-vehicle project in the cold winter.

My exhaust system was otherwise solid. I checked around the area muffler shops and found a guy, who I didn't know, to repair it.

He cut the old converter out and welded in a new one that I bought from the regular auto parts store. Total cost was $300. A sensible price for both of us.

Maybe you can find such a muffler shop in your area? Find out what your local auto parts store charges for a replacement converter, so you have an idea.

I've been a career auto mechanic and this is the first job in decades that I paid someone else to do (besides new tires). My Ranger runs fine.

-Engine overhaul mechanic and general overhaul mechanic since 1972. Retired in 2018.

You have two choices: get the problem fixed or set the piece of junk on firer.