Role of karma yoga in removing or neutralizing our sins. How karma yoga can remove all our sins from the past when we only dedicate the result of our current activities to God?
Karma Yogi (KY), relinquishes Bhoktruthvam (disentangles with the result).
Ensued by a natural tendency of dispassion for sense objects, unlike a Kamya karma doer who strengthens the desirous vaasanas, and gets fixed in janma chakra.
But KY helplessly holds on to sense of I (ahamkara) and so has karthruthvam , hence KYs handle to past karma transactions(sanchitha) is still active and the off loaded portion prarabdha is on effect. So KY may experience the effect of past karma, though with reference to BG 4.21, KYs karma does not incur sin.
nirashir yata-chittatma tyakta-sarva-parigrahah shariram kevalam karma kurvan napnoti kilbisham
(English Translation by Swami Mukundananda)
Free from expectations and the sense of ownership, with the mind and intellect fully controlled, they incur no sin even though performing actions by their body
But a Jnani (one whose ahamkara is obliterated) has no karthruthvam.
So as a corollary Jnani (whose sanchitha has lost its relevance) is free from all sins of past karma .