How to subtract two points on an elliptic curve? Please tell me if there is a formula for A-B, (That is, subtraction of two points / minus). I know how two points are added, A + B this addition is described in detail 

(Please tell me how you can change the formula to subtract two points / minus) A-B
You can negate a point (x, y) by simply changing it to (x, −y).

The document that defines ECDSA reminds us of this fact:

https://www.secg.org/sec1-v2.pdf

Here's a screenshot:



So once you have negated one of your points, just add it to the other one, and you have achieved subtraction.