Can Pitru Dosh be completely removed by performing puja?

Yes. The Markandeya Purana states that Pitru Dosh is a karmic debt, and debts can be fully repaid through the correct ritual. Once Narayan Bali (for unnatural death) or Pind Daan and Tripindi Shradh (for generational neglect) are performed with proper vidhi, the ancestors receive peace and move to Pitri Loka. The active karmic weight behind the astrological affliction is removed, and the obstacles the distressed ancestors were causing — in marriage, career, childbirth, or health — naturally dissolve. However, maintaining the relationship going forward requires annual Tarpan on Amavasya and Pind Daan every few years. The one-time nivaran puja clears the acute crisis; the ongoing practice sustains ancestral peace across generations.