How euthanize without clove oil?

Hi everyone Unfortunately I’ve decided it’s time to euthanize my 4 year old betta. He’s been on and off for the last year and now the last couple weeks he’s been just laying on his side heavy breathing. I don’t see any more hope and I don’t want him suffering anymore.

I don’t have access to clove oil for at least a week so is there any other way to humanely euthanize?

5 gallon planted tank, heater set 80, ammonia 0, nitrite 0, nitrate less than 5 Had him for four years but tank has been set up one year since I last moved, fully cycled Only tank mate is a bladder snail