In Adhyay 18 Shlok 66, God (Kaal) is saying that you relinquishing all my religious practices in me, go in the refuge of one Purna Brahm. I will liberate you from all the sins. Do not worry.
The meaning of Adhyay 18 Shlok 61 to 66 is that Kaal (Brahm / Kshar Purush) is saying that the Purna Parmatma (the other Purushottam / Eternal God – Param Akshar Brahm), who is situated in the hearts of all the living beings, He only causes the living beings to wander like a machine based on their deeds i.e. based on their actions, causes them to revolve in heaven – hell – birth – death and in the 84 lakh births of various life forms. A person, who is not in the refuge of that (Purna Brahm / SatPurush) Supreme God, and worships Kshar Purush (Brahm / Kaal), the three gunas (Rajgun-Brahma, Satgun-Vishnu and Tamgun-Shiv) and the gods-goddesses or does not worship at all, whatever deeds he does, based on them, that omnipresent God (SatPurush) only gives the fruits. Like, Bhakt Prahlad was a worshipper od Vishnu, so for his protection that Supreme God (Purna Brahm / SatPurush) only came in Narsinh form, killed Hrinakashipu and later, showing Vishnu form satisfied Bhakt Prahlad. Of whoever a bhakt is a worshipper, that Purna Parmatma (SatPurush) only protects that bhakt and to maintain the faith of that bhakt, He comes acquiring the form of his deity. Those who do bhakti or who do not, Dharmraj keeps the account of all of them. On the basis of the deeds, gives the fruits as directed by the Supreme God.
He who goes in the refuge of that Supreme God (Purna Brahm) by means of a Complete Guru, that bhakt (yogi) is relieved from birth-death and the births of 84 lakh life forms and goes to Satlok (the true lok, Sachchkhand, the Eternal Place) and becomes completely liberated. God Kaal (Kshar Purush) can also give some temporary liberation (relief), for that Kshar Brahm says that abandoning the worship of Brahma-Vishnu-Shiv and gods-goddesses, by doing unadulterous (with undeviated mind) bhakti of only me (Brahm) after making a guru, you will attain me (Kaal). Then he will grant the fourth liberation (will place one in Great Heaven in Brahmlok) to that worshipper. Then finishing his earnings (merits) will come to an end at the time of Kaal’s (Kshar Brahm) mahapralay (Great Destruction), and then when Kaal (Kshar Purush) will do the creation in that those worshippers with fourth salvation will certainly go to birth-death and in the births of 84 lakh life forms. Because it is the constitution of Kshar Brahm that Arjun whatever action a living being will perform, he will have to experience the results of all those (good and bad) actions. This is a hart and fast rule (opinion). For good actions, heaven and great heaven; for bad actions, hell, and for mixture of good and bad deeds, 84 lakh births of various life forms. This is the result of the sadhna of Kaal (Kshar Brahm) God. Therefore Kaal (Kshar Purush) has clearly said in Adhyay 7 Shlok 18 that those who are striving to attain God those human beings, noble souls, are completely knowledgeable (are knower of my scriptures), but they are properly fixed in my (Kaal’s) anuttam (bad/inferior) gati (salvation) only i.e. because of not being aware of attaining that Purna Brahm Parmatma, they arefully dependent on me (Kaal) only. Because of which they remain deprived of the complete peace (complete salvation). Therefore Kshar Brahm (Kaal) is clearly saying in Adhyay 18 Shlok 62 that go in the refuge of that Supreme God, as a result of which you will attain supreme peace (complete salvation) and the eternal place (Satlok). Then, in Adhyay 18 Shlok 63 to 66, says that Arjun, now you decide whether you want to come in my refuge or want to go in the refuge of that Supreme God. I have imparted this knowledge, the most confidential of all secrets, of that God to you, and listen to my most confidential invaluable words; you are very dear to me. Therefore I am telling you that you go in the refuge of that One (Purna Brahm) Supreme God. He only (Purna Brahm only) is my revered God (deity. if you want to remain in my refuge then you will attain me i.e. will go to Great Heaven; I truly promise this to you. If you will remain in my refuge then you will certainly have to fight. Here, there will be constant struggle. Attaining me will also be possible only when you will do sadhna according to my rules (opinion). If you will simultaneously keep worshipping Brahma, Vishnu, Shiv, gods-goddesses, pitras and ghosts, then also will not attain me because this is adulterous bhakti, which is not based on one God. Further, in Adhyay 18 Shlok 66, has said that if you want to obtain benefits from that Supreme God, then relinquishing all my religious practices in me i.e. also giving up these, go in the refuge of that One (Purna Brahm). Then I will liberate you from all sins. You do not worry.