Your chances to remove 3 URLs from the SERP in just one week are close to zero.
If the keyword these bad URLs rank for is not competitive, you can do a Scrapebox blast with that keyword as a name and in the comment box (write a long keyword optimized comment). Eventually many of these blogs will outrank the bad URLs. This won't work for competitive keywords!
I'm not sure if negative SEO really works. You can try to spam these bad URLs in some low quallity spammed guestbooks, etc. If you run out of ideas this might be worth trying.