Sharepoint - SharePoint 2013: Error while creating lookup column

This is a Known behavior of Calendar list (Event Content Type) in SharePoint.

Work around:

I followed below steps to achieve the cascade delete on Event Content type:

1. I created one custom list instead of Calendar list.
2. Added lookup column from Parent/Provider custom list and set Enforce relationship behavior to Cascade delete.
3. Added Event Content type in lookup consumer list (Newly created custom list).
4. Added newly created lookup column in Event Content type (Add from list columns).
5. Verified deleting items from Parent/Provider list and it automatically deletes event items from consumer list.

Note:

Set Enforce relationship behavior to Cascade delete on lookup column before adding Event content type to consumer list.