You mean something like this?
If I were you I’d get the single use sterile kits- that way you can dispose of them and don’t have to mess about trying to sterilise blades.
The technique is just to cut on one side of the knot, near the skin, and pull the other side of the knot, near the skin so that you lift the suture out rather than pulling it through the wound.
I have a couple of single use stitch cutters at home that I got from work- irishfella has a lot of moles and usually gets one or two biopsied or removed at each annual dermatologist visit. I reckon that by liberating the supplies from work and taking his stitches out myself I’m saving the NHS money because he doesn’t have to go and see a nurse at his GP’s office to get them out.