can i withdraw my ucas application and apply for a different subject

i chose to do law initially but now i want to apply to some other unis to do another subject. im still in the 14 day period so would i be able to withdraw my entire application and reapply or would i have to substitute my choices and send the unis my new personal statement ??? im rlly confused my teachers told me i could withdraw my application and resubmit it but idk 😭

The cancellation form is here: https://www.ucas.com/corporate/application-cancellation-request-form

what reason would i put for me cancelling my application there isnt one that applies to my situation

You have to lie.