You can try it on linux container, since playing in the chromebook directly is trickier

Please read my comment

This is unrelated to the topic but yes 

hihi!! I'm pretty sure based off the website you linked it would be impossible (to my knowledge) to delete Monika given there is no method to access the files neccessary to delete her. However if you're really hell bent on finishing ddlc I'd recommend finding an emulator via playstore that supports pc games like ddlc on your chromebook OR finding an apk of ddlc to play on your phone(if you do choose to do this though keep safe of malcious site, though I do think there is a reputable enough one available..?). Both methods should realistically give you an ability to access the game files and subsequently delete Monika but beyond that I can't think of anything more. Good luck on solving your issue though!