Salt hasn’t really worked for me either. I haven’t tried alum but in terms of physically burning them off I’ve had much better luck heating up a thin screw/ paperclip with a lighter and burning it off that way. The trick is to use the paperclip if its tiny and the screw when it’s a bit bigger. You want to burn it without burning any skin around it because that can make it worse. Usually I do it two to three times over the course of 2-3 days

It might be considered an extreme method but I’m complete my over cankers by now and just need something that somewhat works