Need Tech Support: Unable to clear "No Duplicate Entries" setting

Need Tech Support: Unable to clear "No Duplicate Entries" setting

I originally set a field in a form to "No Duplicate Entries", but now I don't want that condition.

When I uncheck the "No Duplicate Entries" checkbox and click Done, it does not take effect.  Re-opening the dialog shows it still checked.

Then, to try it another way, when I go into Script mode and attempt to remove the "Unique" flag from that field's definition, I get this error message when I try to save the modified script:
Error modifying the page
Columns participating in the Primary Key Definition or Foreign Key Definition cannot be altered : columnName : Event_Name_340313000002095413


I need help please.

The application is:  w21data
The form link name is:   Add_an_Event
The field needing help is:   Event_Name

Please remove the "No Duplicate Entries" condition.

Thank you.