The advantage of having an ORCID account is that it eliminates author name ambiguity and ensures your research outputs are correctly attributed to you. If you have more than one account this becomes harder to manage and creates confusion.
You can find out if you already have an account by trying to register with the email address that you may have used to create an ORCID iD. If you have already created an account with this email address you will be asked to log in rather than to register a new ID.
It's also worth searching the ORCID registry by using the Advanced Search function before you register for a new ORCID iD if you think that you might already have been assigned one.
If you find you already have created an account but don't know the password you can reset it by using the forgotten password link. If you no longer have access to the email address that you used to create your ORCID record, the ORCID support team can help you regain access. Don't create another iD as duplicate ORCID iDs will cause problems in maintaining your record.
ORCID are unable to delete duplicate ORCID iDs. However, you can remove the duplicate from your Account Settings so it refers to your primary ORCID iD. So once you identify you have multiple accounts you need to decide which one you want to retain (primary).
Because ORCID identifiers are designed to be persistent, obsolete iDs will be deprecated, not completely deleted. Data on the deprecated account will be deleted, and the iD will point to your primary record, both in the user interface and the API. An example can be seen at https://orcid.org/0000-0001-6151-2200. To deprecate your duplicate record(s), start by logging into the in the primary account/iD you want to keep, go to Account settings, scroll down to Account actions and select Remove a duplicate record.
Enter the sign-in details (email address or ORCID iD, and password) for the record you want to deprecate, then click Remove duplicate record.
To confirm, click Remove duplicate record. If you have more than one record to deprecate, simply repeat this process for each additional record.