Table 1 shows the number of rules required to extract the main article for each website.
Table 1 shows the number of rules required to extract the main article from each website.
From is the common preposition for "extract", while for is also meaningful as we can say it shows X for each Y. Then sometimes I don't know which is better to be used!
Moreover, removing distracting parts from/on a web page can enhance the page readability
For a simpler task such as extracting the main articles from/on/in/of a news website, the features they provide can be excessive.