removing unused tags from roller

Hi,

One of my bloggers used some tags for articles that were incorrect.  We'd
like to remove them so they are not auto suggested or shown anywhere.
We've removed them from the articles, but they are still in the system.
Can you recommend how to remove them?  Do I need to directly edit the DB?
Is that safe or will it cause problems?

Thanks,
Sean
https://www.militaryhire.com/blog/