You have one script, called PlayerManager.cs, and you use that class as component in other gameobjects.
You decide to change its name. To EnemyManager.cs, so the first problem is that you have to edit the script and change manually the name of the class, and then change every occurrence of PlayerManager in the hole project.
In eclipse for example all these is done automatically when you rename the class.
Also if you move this script to another folder, from unity editor project view, then an error of file PlayerManager.cs not found arises and should not because you have moved the file ( inside the editor of unity))
Create an script for example PlayerManager.cs, use PlayeManager class in other gameobjects.
Change the name of the script to whatver PlayerStatisctics.cs for example. You would have to rename manually file by file all the sites were PlayerManager is used.
Then organize the project, and create a folder PlayerScripts, move PlayerCharacter.cs to that folder ( in the project unity editor view). Then an error PkayerCharacter.cs is not found arises...unity