You can not simply remove blocks form a mod, you would have to get the jar to a folder. Next u would need permission from the moder to do this because most of the time they say: "Do not modify without permission!"

Why do you even have to get rid of the blocks cant you just ignore them

You delete blocks in content folder, crashes game, the mod will still try to find the code you deleted, as they are used somewhere else in the mod, unless you re-write the coding of the mod, you wont be able to remove the stuff you want, when you create a block, you do some importing and exporting, and if its a complicated mod that the one you are using, then you just cant do that, the code is probably found throughout the mod for those items, remove their classes, you have errors, those errors, cause the game to crash, you kind of made a stupid move deleting those files. - Source, I mod, I know.

One can not simply remove blocks/items within a mod. If a config file was setup with the mod to disable certain blocks, it's possible. Sadly though, you can't do it with this mod. If you really really want to change this mod, you'd have to rewrite the code and remove the stuff you don't want.