Just in case you're talking about the Scripture Mastery app (and not the Gospel Library app - even though that's the forum we're in):
1. Tap the drop-down at the top left, which lets you pick a book of scriptures or "My Scriptures"
2. In that drop-down, note the pencil icon next to "My Scriptures". Tap that icon.
3. Check the box next to the ones you want to remove. After tapping the box, a trashcan icon will appear in the toolbar. Tap the trashcan icon.
Hope that helps.
Liz