Delete a top-level pageGroup construct from page-groups.apx.
Blocks when any page still references the group via pageGroup: @<id>
(those pages are listed); —force to override. Forcing leaves the
referencing pages with a now-dangling pageGroup reference, which SQLcl’s
apex validate --official will likely reject — clear or reassign them
first with uc-apx edit page --clear-page-group.