hide rows

hiding means the rows stay in the file but are not displayed — a hidden row's data, and any formula depending on it, is completely unaffected; only its on-screen visibility (and, by default, its inclusion in things like printing) changes. Selecting by row headers (not cells) ensures whole rows are hidden, because Hide is a row/column-level command: selecting cells and trying to "hide" them has no equivalent action, while selecting the row numbers themselves targets the entire row as one unit. Do not delete them: deleting removes the data permanently and renumbers every row below, which would silently break any formula referencing those rows by position.