Remove all spamy backlinks to reduce your website spam score, this is the only method to reduce spam score quickly, it's my personal experience I reduced spam score from 30 to 9 of an website about blogging.
What I did:
- Analyze backlinks profile
- Make a list of spamy backlinks
- And remove all backlinks
- Finally spam score reduced to 9
Note: It may take 2 to 3 months.
