There are two ways to share the admin rights of a poll.
1. When you created the poll, you should have received an email from Doodle with the title of your poll and a button for inviting participants. You have the possibility to forward this email containing that button to as many people as you would like. Anyone who clicks on that button will be taken to the admin page.
2. You can also edit the poll (open the poll, and click on "more" and then "edit"), and in step 4, "Tell your participants who you are", change the email to the one you want to give the admin rights to. The poll will then appear in the Dashboard of the account you shared the rights with.
Be careful! New admins also have the option to delete participations as well as the poll itself.
If you no longer have the admin email, have it resent here: https://doodle.com/help/lost-and-found
NOTE: Changing the email of the poll will transfer the admin rights, but it will not change the notification flow. Updates on the poll will always go to the original creator email of the poll. If you wish to receive updates on a poll you did not create, you have to vote in the poll yourself and select to "subscribe to updates".