I need to delete a picklist value. Will that affect my previous data in the reports ? What will happen to the records that previously used this value ? FYI - I don't want to replace the value with anything I just need to delete it.
They will stay right where they are. Picklists are more like "combo boxes", in that they'll show a strict list of options, but allows other values through Apex Code, API calls, or even surviving the deletion of the picklist item. That value will remain on all existing records until it is changed to a new value (e.g. a user edits the record and changes the value), in which case that record will no longer be able to have that value selected through the UI.