You need to log in with an Administrator account, and then you can add/remove other Administrators. https://documentation.meraki.com/General_Administration/Operate_and_Maintain/Managing_Dashboard_Access/Managing_Dashboard_Administrators_and_Permissions If you don't have any accounts that work, add the old employee's email address as an alias to your email account, perform a Meraki password reset, log in as that account, and then update the Administrators.
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