The phrase "unfettered control" means having complete and unrestricted power or authority over something or someone, without any limitations, restrictions, or obstacles. Full definition
Districts then had nearly unfettered control over how these funds were spent; activities merely had to comport with four major federal education statutes, including the Elementary and Secondary Education Act — laws that, despite many years and billions invested, hadn't adequately improved our schools. (educationnext.org)
A successful Android root exploit effectively gives hackers unfettered control of a user's smartphone. (sciencedaily.com)
As the event page notes, ESAs give families almost unfettered control over the public funds allocated for their child's education. (educationnext.org)