4 official rulings from Bandai. Straight answers to how this card actually resolves.

Does this card’s <When Digivolving> effect force me to trash 1 card in my hand when this card digivolves?
Yes. If possible, you must trash 1 card in your hand for this card’s effect. “Then, you may play 1 purple Level 4 or lower Digimon card from your trash without paying its memory cost” is phrased “you may,” so you can choose whether or not to play a card using the effect.
Can I use this card’s <When Digivolving> effect to trash a purple Level 4 or lower Digimon card in my hand, then play it with this effect?
Yes, you can.
I use this card’s <When Digivolving> effect to trash a card in my hand. Does this card’s <Your Turn> effect trigger?
Yes, it does.
When happens when this card’s <When Digivolving> effect activates while my hand is empty?
You can’t trash a card in your hand, but since you don’t need to trash a card to activate the second part of the effect, you can still play a purple Level 4 or lower Digimon card from your trash without paying its memory cost.
Got a line that uses Titamon? Map it in the builder and share it with a link.
Questions and answers are Bandai's official rulings, collected and translated by the DigimonCardGame Wiki community and reused here under CC BY-SA. Card names and card text are © their respective publishers; Combalo is not affiliated with Bandai.