demote from

demote (someone) from (something)

To reassign someone to a less important role or position. I'm worried that I'll be demoted from team manager if the boss finds out this blunder was my fault.
See also: demote

demote someone from something (to something)

 and demote someone (from something) to something
to lower someone's rank from one rank to another. The manager demoted Bill from cashier to clerk. The army demoted her from lieutenant to sergeant.
See also: demote