Hey @gariggantulga 👋🏼
Your absolute easiest option would be getting in touch with the old administrator, if they no longer work for the company but used a corporate email address within your control, you could also work with the responsible team to access their mailbox / recreate the email address and use it to reset the password.
Should you not be able to do this, open a Support case. This must be done via a written form of communication, as you don't have dashboard access, use this link: https://meraki.cisco.com/meraki-support/open-a-support-case/
You will be expected to prove ownership and there is no guarantee Support will be able to assist. As per the Meraki Offer Description:
“5.2 Limits of usage. You agree to use the Product only in accordance with the Cisco Meraki Documentation available on Cisco Meraki’s website, and You (not Cisco) are solely responsible for maintaining administrative control over Your Dashboard account..”
When if/when you do regain access, ensure you create a backup account to prevent future occurrences of this.