Will someone have access to your wallet without your device but the person manage to see your private keys and copy them without your knowledge. Will the person be able to withdraw your money or change password and block you from having access to your wallet?
Should I just say your private key is your money, anybody that can have access to your private key already have access to your money, they can move out all the coin in the wallet at any moment they like, that's why private key should be protect very well, if anyone have access to your wallet private key, the person won't be able to change your private key, you can't change a private key, but the person can just create new wallet and send all the coin you are having to the new wallet, then the person will leave the wallet empty for you, the person won't stop you from having access to your wallet, but you won't be able to have access to your coin anymore.