According to Role hide the section

Show Fields on the Basis of Security Role of Current User Using Javascript in MS Dynamics CRM

If you want to show/Hide or Lock/Unlock specific field instead of a whole section you can just replace the "ShowHideSectionAccordingToRole" function with the below function :

function ShowHideFieldAccordingToRole()

{

if(CheckCurrentUserRole("CSR Manager"))

{

//Show the Field

Xrm.Page.ui.controls.get("FieldName").setVisible(true);

               //To UnLock the field

              // Xrm.Page.getControl("FieldName").setDisabled(false); 

}

else 

{

//Hide the Field

Xrm.Page.ui.controls.get("FieldName").setVisible(false);

               //To lockLock the field

              // Xrm.Page.getControl("FieldName").setDisabled(true); 

}

}