Following are the conditions for Revocation of gift.

(1) A gift may be revoked by the donor at any time before delivery of possession. The reason is that before delivery there is no completed gift at all.
(2) Subject to the provision of subsection (4), a gift may be revoked even after delivery of possession except in the following cases–
(a) when the gift is made by a husband to his wife or by wife to her husband;
(b) when the donee is related to the donor within the prohibited degrees;
(c) when the donee is dead;
(d) when the thing given has passed out of the donee’s possession by sale, gift or otherwise;
(e) when the thing given is lost or destroyed;
(f) when the thing given has increased in value, whatever, be the cause of the increase;
(g) when the thing given is so changed that it cannot be identified, as when wheat is converted into flour by grinding;
(h) when the donor has received something in exchange (iwaz) for the gift.
(3) A gift may be revoked by the donor, but not by his heirs after his death. It is the donor’s law that will apply to a revocation and not of the donee.
(4) Once possession is delivered, nothing short of a decree of the Court is sufficient to revoke the gift. Neither a declaration of revocation by the donor nor even to revoke the gift.

Donor can revoke the gift at any time before delivery of possession and if the possession is delivered then the donor can only revoke the gift through a decree of the court.
2019 CLC 309

Gift—Meaning and scope—
Hiba or gift is “a transfer of property, made immediately, and without any exchange,” by one person to another, and accepted by or on behalf of the latter. A donor can part with his property through a gift either orally or through a written instrument. No transfer of possession is required in the case of a gift by a father to his minor child or by a guardian to his ward.All that is necessary is to establish a bonafide intention to gift.
2019 CLC 309