@IlariaHenein
When you say archive, what would you like to have happen with the courses?
We haven't started archiving yet, but we are beginning to discuss what we plan to do. So far as an initial step, we have set-up additional sub-accounts that will serve as as a first step to our archiving, but we haven't moved any courses to them yet. This should help make it easier to run account reports on active courses and ignoring archived courses. It will also allow us to set-up different permissions for archived courses compared to active courses.
You may also be interested in the process shared by @lmsstaff on the script they use at their school for archiving courses: How to Archive Courses via Python