You can drop a designated number of lowest scores in a Moodle grade category, as long as all items in that category are worth the same number of points.

11. On the applicable category, click Edit, then Edit settings.
    
12. Click on Show more...
    
13. Type the number of scores you'd like to drop.
    
14. Click on Save changes.
    

ℹ️ Note: the score for that category will show as 0 until the "drop the lowest" threshold is exceeded, as Moodle will consider the prior attempts as the lowest.