[Koha] Exclude users from search (check out)

[zefanja]

Hello,

we use Koha in our school and therefor many students get enrolled each
year, but also many students leave the school every year. Every year we
have more and more users, that are not at school anymore, but they still
exist in Koha. If we want to checkout books and search for the right
user we have many similar names over the years, sometimes the same
firstname and lastname.

Is it possible to deactivate users so they are excluded from the search
result (checkout)? I don't want to delete them because we will loose the
circulation data.

Regards,
Stephan