If you have another admin user, he can re-create it. That should be the case if you were allowed to delete the admin. Whichever user had the most rights is now the admin.
If not you will have to go through the drop the admin table recovery as in the troubleshooting guide on forgotten passwords.
Maybe I misunderstood the question then: I was referring to as "not possible" that a deleted database entry is deleted and there is not trash to get it back. Of course re-creating a similar account is possible.
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If not you will have to go through the drop the admin table recovery as in the troubleshooting guide on forgotten passwords.