I know I know, you got those tokens "airdropped" to you, and you went to the site, and tried to sell them cause they said they where worth so much and greed got the better of you. 

Then the panic sets in when you realise you cannot in fact sell them, and that this is a dusting attack, and now your BNB tokens are in danger because you signed the contract allowing unlimited spending on your BNB.

Worry not, for here is how you revoke the allowance you have just given the website to spend your BNB.

I figured this out when I fell for the Minerium dusting , honeypot scam, but it could be any of the other scum that has arrived into your wallet. I personally now have a nice collection and when someone figures out how to safely turn these into money or NFT'S, I'll be set up for life. Lets put it this way. Of the 27 tokens BSC scanner has detected in my wallet, 9 of them are ones I bought, and one of those is BNB.  The rest just turned up, and the websites look super suspicious, case in point below. 

Broken English, check. Oh wow, the exact amount of tokens I received without even connecting my wallet, check.  And I just got given more than 7 BNB worth of tokens? Yeah, a totally legitimate website.  I'm not putting in any link to this website, since I don't want to drive any traffic to it. 

So there are a two places I've found and used you can go to.   

Beefy finance allowance, or you can go here http://bsc-allowance.beefyfinance.vercel.app/ just to interact with the app itself ( the website seems to be having troubles with its security certificate as I write this, but I have used the site previously with no problems ) . I used this first as I was already using Beefy and trusted it more. 

Only downside with Beefy is you have to click on the first address which takes you to BSC scanner and then you know which token it is referring to. So can take awhile to find the right allowance to revoke.  

The more user friendly website is this https://app.unrekt.net/ .  This allows you to check all your allowances not only on BSC, but also ETH, HECO, FM and Matic .  Just connect your wallet in the chain you want to check, and go down the alarmingly long list. When you come to the dusting coin, you hit revoke.

Unrekt and beefy ask for some BNB to carry out the transaction ( the same amount you used to sign the allowance, usually around the 11c region ) , and voila, now these scum do not have allowance to spend you hard earned BNB. 

Hopefully this helps someone. I'm not saying you can now try selling all those scum coins safe in the knowledge you can remove the approval. First you will not get anywhere near enough money for those coins, if you can sell them at all. Second, you need to spend at least 22c each token to approve allowance, and then take it away. Third, if you are unlucky and they empty you out while they still have allowance to do so, there's no getting your BNB back. So just let those token lie in peace until some clever clogs figures out a way to safely get rid of them. 

I'm actually glad I took the time to write this, as I spotted one scammer that slipped through the net. Alpacafin.com, not to be confused with the better know Alpacafinance.org, which I also had at one point. 

EDIT:  Thank you cryptoplankton for raising a good point.  The reason I trusted Unrekt in the end, was because both of the two methods above do not set up an allowance. You give them access to view your contracts, and then literally pay them to remove an allowance, and that is all the money they are able to access. There is no setting up contracts or allowances with insane spending limits like pretty much every website you've been on. Normally you unlock a wallet, or sign a contract which you pay, then you pay again for each transaction, having given the website permission to take money out of your account. With the two methods above, you literally hit revoke, pay that transaction, and that is all they are able to take.  You can test it out on a throwaway account, and use the other method to make sure the allowance has been revoked, and that no new allowance has been granted for beefy or unrekt.  At the end of the day, it came down to me making a one off payment to an app for 11c, or trusting the scammers won't take my BNB.  Just make sure you are on the official unrekt website.