All the times I've successfully quit things - opiates were the hardest, but this worked for cigarettes and weed too - I quit before I used up whatever stash I had, and you're right, just knowing that I had that little thing tucked away made it so I didn't feel like I had an excuse to go get some just in case and then dip into that stash because why not. I just kept it there for "an emergency," and then kept telling myself that everything that happened didn't quite rate "emergency," so then I had to figure something else out, and then eventually I just didn't even really consider the stash anymore.
So maybe this method could work for you too? ❤️ I know you're struggling and needing a change, and I hope you find it.