Is there a way to remove the hyperlink for the Issue Key that is brought in to smartsheet via the Jira Connector?
The hyperlink added by the Jira Connector into your Issue Key column can't be removed at this time. Please feel free to submit an Enhancement Request for this.
As an alternative, I'd suggest adding a helper column in your sheet that populates only the Issue Key text, then hide the Issue Key column used by the Jira Connector. See the example attached.
Hope that helps!