Clerks are what we call all the staff members you want setup in the system, Individual clerks are given unique login codes that identify them in the system.
Clerk are found under Setup > Clerks
Clerks can be given any login code as long as it isn’t being used by another clerk, when adding a clerk the fields you need to look at are Name, Login Code and User Permissions. You can discontinue a clerk at any time by modifying it and ticking discontinue. See below for example with highlighted fields.