How do I delete some songs from my Songbook?

Hi!
There was a problem on my android app a few weeks ago and it copied almost all the songs I had-then more than 300 apperared-, I reinstall the app but the problem still, then I tried (in the smartphone and pc) to delete the songs one by one until only the pieces I wanted were on the list -it took me hours!, but it didn't work so I still have those songs repeated and some others I don't want to keep on my SB.