Is this true??

I’ve been told you cannot demote as a shift after getting the position. I’ve been completely drained and stressed after getting the promotion. I haven’t taken the manager food handlers test as I failed it twice and have to wait to take it again + pay for it. I’m thinking about flaking to my manger about it and asking if I can demote if it is possible. If not, I’m just going to look for another job I’m ok with the pay cut.