You can remove Manager access from an Agent user logging in to your RPM and simply make them a Rep user. Manager users have full access to their Agency and will be able to see any Referrals or Adjustments assigned to them as well as setup Transfers if they have their own RPM subscription. If your Rep does not have any assigned Referrals or Adjustments, then nothing will change for them.
To make a Manager a regular Rep user, go into the Top Menu >> Reps >> Select the Managers tab >> select a user.
Under the More Menu, click Trash to remove their Manager access.
Click OK. Checking off the "Also trash the rep" box will trash the entire user.