My guild doesn't use DKP Snap shot , we use a different loot system.

Is there any other way of getting rid of characters that are no longer in guild in an automated way ?

Second question is there a way to ask all users to re-activate accounts in order to get rid of inactive accounts.

Thanks

If you import roster from armory it will ask you if you want to delete any that are not in the guild anymore.

Not really, I'm afraid.

You'd have to delete the accounts and have them re-make them, but that would break their post counts and the like (since they'd be different accounts).

You COULD tell everyone that if they haven't logged in in the past X days, that you'll delete their account, then after X days, head to Admin > Characters and Accounts > Website Accounts, then use the "Select Accounts" box in the upper right to highlight the inactive accounts (specifying the number of days). And there you can delete those particular accounts.