Deleting a field will leave orphans

There is clean files too. That one is exactly what it is doing. But please make backup of files before do :)

I'll explain the process.

When you delete field all field values are deleted from _js_res_record_values. When you start cleaning process it selects all record IDs that are connected to upload fields somehow. Then, it gets list of the files from _js_res_files table which are not binded to those IDs. It is the list of files with deleted field. We delete all files and clean files table.