Start with the right checks.
The warning may concern working space on the computer, cloud storage or both. Read the exact message and check the intended account.
What to do next.
Record the error and whether it appears in Windows or OneDrive.
Check available storage on the computer and the account’s cloud storage status.
Review recognized local files and approved storage options before deleting anything.
Keep important unsynced changes safe while the shortage is resolved.
Check the result.
Confirm that the warning clears and a small test update reaches the cloud account. Check the file’s contents, not just its name.
Stop and get help if…
You cannot establish where the shortage is, files are shared with others or the only copy exists locally. A storage review should precede bulk removal.