Don't delete it. Deleting an article has the lowest effort:effect ratio, so lots of automatic policies are in place to speedily allow an author to restore a page that's been deleted.

If the article itself shouldn't exist, mark it with {{qd|spam}} . `qd` is quick deletion.

If the article should still exist but has substantial content that's advertising, mark it {{npov}}

In both cases someone else will come along and fix it. If the author who put the ads up in the first place removes your template, just put it back up.