At any point during your turn except during combat or Running Away, you may discard Items worth a total of at least 1,000 Gold Pieces and immediately go up one level. (“No Value" cards are the same as zero Gold Pieces.)
If you discard (for instance) 1,100 Gold Pieces worth, you don’t get change. But if you can manage 2,000 worth, you can go up two levels at once, and so on.
You may sell Items from your hand as well as those you are carrying.
You may not sell Items to go to Level 10.