I'm a windows user so if your using something different I don't know if it will work or not. If you go into your files go to the your game files of extra curricular activates, then click the game folder, then go down to the saves folder, that has all your data in it. you can move it out of that folder and it wont read it so you can save those files which is not permanent or delete them and that is permanent. then load up the game after you have done that and if the game is open when you do that you will have to shut the game down then start running it again.
Okay so on windows it has a hidden folder that backs up the saves so you might need to go their. in your file explorer go to this PC then windows C:, then Users, click on your profile folder (the name is different on everyone's pc) and open it. now on the top click view and their should be a check box somewhere on top that says hidden items, you want to make sure that it has a checkmark so hidden items will be shown. then a folder called appdata should appear open that folder then open Roaming then RenPy then look for extracurricular activities. (I have added a image so you can find the view and hidden items check box). that file has a backup of your game saves so deleting this file or just moving it should solve your problem. If you get stuck at any point from my explanation I can try to help. ^-^