Automate assign/remove roles to/from users every month

Hi,

We have a request to assign all users to RoleA, RoleB at calendar month end. Then after calendar month end, to remove RoleA, RoleB from all users and assign all users to RoleY, RoleZ.

I'm currently doing it thru SU10, adding and removing roles to users at calendar month end.

Is it possible to automate this (assign roles to users then remove roles from users) for every month? May I know the detailed steps to do it?

Thank you.