If you're paying for inactive users on Google, here are a few things to consider:
Deleting a user will permanently remove them from your Google services. You will have the option to transfer all of their data to another user before deleting them, so you can retain any information needed. The upside of deleting a user is that you will no longer be charged a monthly fee. While you can restore a deleted user within 20 days, the downside is that once that time has elapsed, all data will be lost. (Read more)
Suspending a user will temporarily block their access to your Google services. The upside is that you can re-instate them at any time. The downside of suspending a user is that you will still pay a monthly fee on many account types. You should only choose this option if you intend to restore access at some point. (Read more)
Creating a Group is a great option when you have an external- or internal-facing email address like jobs@ or hello@ that doesn't need a dedicated mailbox. Rather than creating a user/mailbox, you can set up a Group and have all email sent to that address automatically forward to as many other emails as you'd like. The upside of creating a group is that there is no monthly charge and you can have as many groups as you like. The only downside is that it takes a little extra work to set-up a reply-from email in Gmail if you need one (Read more)
PRO TIP: When setting up a group from your admin console, make sure to allow External users to "Publish posts" to your group or else outside emails to the group will not get through.
By Deleting inactive user accounts and Creating Groups, you can dramatically reduce your monthly Google bill and ensure that you're only paying for the mailboxes that you're actually using.