You can delete courses and programmes up until selection begins for the application round for which you've applied. Selection usually begins about 3 days before admissions results are published. Log in to your account on Universityadmissions.se and go to your application. You can make your changes there - just follow the instructions.
After you receive your admissions results, if you've been offered a place but do not wish to accept it, please be sure to decline your offer. This notifies the university that you will not be attending and makes the place available to another applicant on the waiting list.