By mistake I had given a Sapa (Curse) to somebody but later I realized I should not. Is there any Sapa Vimochana mantra for overall?
Curse and blessing is just an assumption of the mind. The jiva’s course is predetermined, and any external factor cannot alter the course. If the person you have cursed has to suffer he will, you cannot alter it. You are just used as an instrument by the almighty to satisfy the course he has set. So do not worry. But do refrain from such acts hereafter.
You may use Sarva Mantra Utkilana Shapa Vimochana -in Shiva Rahasya, Devanagari Tantra