make the fields in booking form conditional

its not an issue per say but the password field (if the user already exist) gets disabled with red writing that no password is needed (the english needs to be corrected there btw) which mostly confuses our customers as its operating in kuwait and the people there are a bit slow tech wise, they think that there is some problem and they are unable to write in the password field causing an issue. if its possible to make that field conditional forexample if user already exist then make the password field hidden and if user doesnt exist then passowrd field will be there making it clean and easy.