HOW DO CUT AN O-RING GROOVE IN THE FACE OF A CYLINDER?

Here it is.

Hi Vignesh,
If you are modelling any cylindrical objects with internal cuts, draw the profile with axis and use "revolved extrude" option (SOLIDWORKS). It uses one feature covering most of the requirements and easy for future modifications.
Next time when you post question please specify which software are you using and provide with necessary images for good chances of response.
Good luck.