What a commentless one-star means
A one-star with no text gives you nothing to act on, which is the frustrating part. It could be a genuine unhappy customer who didn't elaborate, a misclick, or someone reviewing the wrong business.
Without content, you can't know — and neither can Google, which is why it's hard to remove.
Can it be removed?
A low rating on its own isn't a policy violation, so it generally can't be removed just for being a silent one-star. Removal needs evidence of a rule break — for example, that the person was never a customer or it's a competitor.
If you have that evidence, report it; if not, removal is unlikely.
How to respond
Reply professionally even without details: thank them, say you'd genuinely like to understand what happened, and give a direct way to reach you. This shows future readers you care and invites the reviewer to engage.
Sometimes a measured reply prompts them to explain — or to revise the rating.
When to report
If you can show it's not from a real customer, comes from a competitor, or is part of a suspicious pattern, report it for that specific violation with evidence.
Don't report it just for being unfair — that won't succeed and wastes effort.
Offset it with volume
The most reliable fix is dilution: a steady stream of genuine reviews shrinks the impact of one silent one-star on your average.
Keep asking happy customers, and the outlier fades into the background.