First of all, lemme say your parents are good ones, course they seem to care about you.
Today most parents just don't care about what their childs are watching, playing or listening to.
Others simply don't know there is content in games, films & music which is inappropriate for children or how to use perental control systems on PC, consols or even pay TV boxes.
Unfortunatly (for you) all the commands supposed to reduce blood and gibs, are only working with the original valve games, not the mods.
Idk how young you are, maybe wait another year or two till you're allowed to play these kind of games, or convince your parents that you can handle this grade of violence.
Tell them about the positive effects of the games, like teamwork, training your reflexes, etc.
Also if you're playing a game for a while you won't even recognize the Blood anymore, while ppl watching these scenes passive might still see only blood and violence.
If you could encourage your parents to play the games for some time before they decide to allow/disallow them, they might learn to see this the same way.
If you ask me, disabling the blood doesn't make a game less violent, it's just like making violence appear more harmless. This is exactly the oposite of what ppl try to achive with censoring.
Oh, and instead of deleting the blood decals you should replace the .vtf file with another one.
Either you open it up in an image editing software and change the color to something else not reminding on blood or you make the alphachannel completly black, so it'll render invisible.
Next save the file as .vtf and replace the original one.