Can I activate this card's [Main] effect even when my opponent doesn't have any Digimon that can be deleted?

My opponent has a Digimon with 4000 DP or less. Can I meet the "if this effect didn't delete" condition in this card's [Main] effect by not choosing a card to delete?

My opponent has a Digimon with 4000 DP or less. Can I meet the "if this effect didn't delete" condition in this card's [Main] effect by choosing an opponent's Digimon with an effect that prevents deletion and 4000 DP or less?