A categorised table can resemble a set of collapsible headings, but its headings may represent actual record values. Before tidying a group name, decide whether you intend to reclassify the records or only change how the report is arranged.

Use a copy of a small categorised table. Keep an identifier column visible and record several identifiers with their current category values. For example, an equipment list might contain the categories Workshop and Store, each containing two recognisable test records.

In Numbers on Mac, renaming a group in its summary row automatically updates that group’s source-column values. Renaming it to an existing group’s name merges the groups. By contrast, changing group order uses the summary row’s left-hand square as a drag handle. Collapsing uses its disclosure triangle. Delete Group deletes the group’s data too.

Separate a label correction from a view change

If Workshop is simply misspelled and the records genuinely belong to that category, a rename can express the intended correction. After changing it, inspect the source value beside each recorded identifier. Check a record in Store as well; it should remain outside the change.

If you merely want Store displayed first, reorder the group rather than changing its name. Compare the identifier-category pairs before and after. The visible sequence may differ while the classifications remain the same.

Treat a merge as a separate data decision. Two departments with similar names may still represent different responsibilities. Confirm that the merged classification is meaningful before making their group names identical.

Verify the records after an organisational edit

Expand the affected group and inspect its first and last records. Compare the number of records with the original copy and check any report that uses the category. A tidy heading is insufficient if a reclassification changes the meaning of a downstream total.

If the objective is only to hide detail during a presentation, use the collapse control and confirm that the summary remains visible. Do not use Delete Group as a way to remove an unwanted heading while expecting its rows to survive.

Record the accepted category change with the workbook, including whether it was a spelling correction, deliberate reclassification or display-only rearrangement. That short explanation helps the next editor avoid repeating a data change while trying to reproduce the same visual order.

Reference: Apple: modifying Numbers category groups.