UPDATE: Please ignore...I found the answer. Once the issue is opened, the Configure selection (gear-wheel at far-right) brings up the Labels list; from there individual labels or the entire set of labels can be removed.
I added Labels to new Jira issues when importing from ServiceDesk. Now, I feel that I can remove some/all of these labels. I've read the support docs on how to remove labels, which mention that an Edit Icon (pencil) appears to the immediate right of the "Labels" field name when the issue is opened.
However, I do not get the "Edit pencil" icon for Labels; I get the "Push pin" icon. I'm using Jira Cloud on an extended trial; is there an "Edit Labels" feature in Jira Cloud (trial)? If so, how do I access it?