How do I edit field type in my BigQuery Schema?

[ramyofficial]

One of the fields I use in BigQuery has changed, I was using Unix/Epoch timestamp and it caused issues on another system integrated into BigQuery. So I have edited that field on the table to be an ISO 8601 date like "2023-11-17T18:54:37Z"

Unfortunately, the way BigQuery reads the data according to the schema, it returns "2023" and ignores the rest.

I just want to make a change to the schema which currently identifies that field type as "INTEGER" and I want to change to "STRING" I see absolutely no way to do it - I press "edit schema" and there's no way to change anything and I am the project owner there are no more permissions for me to add.