I'm 15, & my dream is to be a singer. I've made 15 songs. My parents took away my notebook, saying my songs are too dark. What should I do?

Make songs that are
1. Dark in a musical theatre or orchestral way ex: Sweeney Todd, les mis
2. Don't use any heavy metal or anything with much electric guitar.
3. Keep making music!
Optional 4. Try making a song maybe about something sad becoming good..., up to you

Well, start listening to happy songs, and then write happy songs.
What you should consider doing if you can write dark songs is write musicals.

What are your songs talking about?
Maybe I can give you some suggestion after I know what those songs about

Don't write dark songs.

write less dark songs ..