GM: Pranam Guruji! I have read about Ishopanishad mantra 3 in one of the website.It says that if we have committed any sin(s) (even serious) and if we surrender ourself and evil thoughts to Ishwar, we can remove our guilt and start life afresh. We need not ask forgiveness from the person against whom we have committed sin because in real scenario, very rare people can forgive serious sins. Is hiding sin is again a sin in this context? What should be the way to remove guilt from the mind? We hear that one should forget the past and live in present. But unless the guilty thoughts of past doesn’t go from the mind ,it is very difficult to live life. And ending life is also sin. Please answer.
Swami Ram Swarup: My blessings to you. The idea of the shloka quoted by you is that he who kills his soul (kills himself) he, after death, gets next births in the lower species (like animals, birds etc.) where there is no scope of gaining knowledge.

Secondly, as per Yajurveda mantra 7/48 we, the human beings are free to do sins or pious deeds but result is awarded by Almighty God. Therefore nobody is empowered to excuse the sins. So, no question of asking for forgiveness.

There is only one way to remove guilt from mind that we obey the preach of Almighty God framed in Vedas. According to Vedas, the sins are destroyed when a person performs Yajyen, daily hawan and practices Ashtang Yoga under the guidance of a learned acharya of Vedas and Ashtang Yoga.
So, naturally human life is full of sorrows, misunderstandings, tensions, problems, sickness etc., in the absence of worship of God according to eternal knowledge of Vedas which emanates directly from Almighty God in the beginning of every creation.