Go to
https://telemarketing.donotcall.gov/ to register to get access to the DNC list. I think you get 5 area codes for free.
You'll need to get some software to do the scrubbing of your list against the downloaded DNC list. In my area at least, there is no practical way to do it manually, the DNC list is far to large. The software I use is no longer available, so I have no recommendations on what is good for this.
Dan