There are work units for tiered storage for removing objects either in the local database or in the shared bucket. Those workunits are named WT_TIERED_WORK_DROP_LOCAL and WT_TIERED_WORK_DROP_SHARED.
These work units are NOT used during a session->drop() call. They are perhaps poorly named and confusing. We should consider renaming the work unit macro to avoid the word DROP. Some possible naming replacements for DROP:
Currently the WT_TIERED_WORK_DROP_SHARED is not used. It is anticipated to be used for garbage collection. (It does have a use/line in the code to call with it to avoid script "unused" errors however.)
The WT_TIERED_WORK_DROP_LOCAL is used to remove local objects from the database when the local_retention period expires.