On Yom Kippur, G‑d mercifully erases all the sins we have committed "before G‑d"—but not the sins we may have committed against our fellow man. If we really want to come out of this holy day completely clean, we need to first approach any individual whom we may have wronged and beg their forgiveness. ("Asking Forgiveness", chabad.org)So you should ask forgiveness from your fellow man before Yom Kippur or Erev Yom Kippur. This reminds me of a teaching of Jesus in the New Testament.
22 But I say unto you, That whosoever is angry with his brother without a cause shall be in danger of the judgment: and whosoever shall say to his brother, Raca, shall be in danger of the council: but whosoever shall say, Thou fool, shall be in danger of hell fire.
23 Therefore if thou bring thy gift to the altar, and there rememberest that thy brother hath ought against thee;
24 Leave there thy gift before the altar, and go thy way; first be reconciled to thy brother, and then come and offer thy gift.
Mark 11:25-26And that is repeated in the D&C
25 And when ye stand praying, forgive, if ye have ought against any: that your Father also which is in heaven may forgive you your trespasses.
26 But if ye do not forgive, neither will your Father which is in heaven forgive your trespasses.
D&C 64:10 I, the Lord, will forgive whom I will forgive, but of you it is required to forgive all men.
D&C 82:1 Verily, verily, I say unto you, my servants, that inasmuch as you have forgiven one another your trespasses, even so I, the Lord, forgive you.