Amanah — faithfully discharging what is entrusted to you, whether property, secrets, responsibilities, or rights — is a core sign of true faith, and its betrayal is a mark of hypocrisy. Allah commands, "Indeed, Allah commands you to render trusts to whom they are due" (Quran 4:58). The Prophet (ﷺ) listed betraying a trust among the three signs of a hypocrite: "When he is entrusted, he betrays." A believer therefore returns what is owed, guards what is confided, and does his duty even when unseen.
Informational, not a personal fatwa. Consult a qualified scholar for rulings on your situation.