immigration at airport ? if it's at the office they can't cancel it as you are automatically without visa and still inside the country . but i have many friend who was on ED visa and jump to non-B and never have problem to change it . but anyway we all got our experiences
in my case no , in the case of some close friends yes . anyway to apply non-b you have to get out right , apply outside Thailand ( i not mean the 1 year renewal but the first 3 month non-B before getting the work permit ) . you fly out stamping you passport out and when you come back just tell immigration you change visa .... but never go to immigration before fly out and ask then to cancel it . does it make sense ?
you can apply any visa even if you already have a visa , then cancel it if you want . as you have to apply outside and online now it will be the immigration at the airport who will cancel it for you on your way back with the non-B visa
what visa you got O or B ?? he actualy talking about non-B visa mean for people work in Thailand . non-O for married , retire .... can work as well with work permit .but without taxs paid in Thailand when you got WP you can't renew it or you have good audit make fake balance sheet