ORCID iD's that end with an X are valid and correct.
The last character of an ORCID identifier is a Checksum. It ranges in values from “0” - “10,” with X representing the value “10.” The Checksum ensures the other 15 digits of your identifier form a coherent iD.
You can learn more about the structure of an ORCID identifier here.
Identifiers are randomly assigned, and cannot be changed.