What To Do With Indexed Unwanted Parameter Urls?

I noticed in google search console that many URL's with a strange "_hstc" parameter were getting indexed.

I have now discovered it this was from HubSpot with a new setting that was enabled.

To avoid any duplication issues it's best these are not indexed I assume. Is this the best method or is it better to try set up canonicals?

• Add instructions to the robots.txt to block crawling of these URLs
• Remove request the indexed URLs

Any help or advice would be greatly appreciated.