Please help- badly healed laceration itchy and raised- want to know best way to heal it surgically? (photos)

I have a wide and raised scar on my thigh due to self harm. It is red and itches, I did this about 7 months ago and it has healed badly as I just left it to heal without stitches using plasters. My plan is to cut it out myself and stitch it up using steri strips or butterfly stitches. I am worried that my skin won't stretch over the site once the scar is removed? I did think of cutting a line through it but that won't do anything as the scar tissue is too hard now.