To clean up the space used, user needs to clean up the Index database one by one. 

Note: if the source code is no longer needed, to free space, user can directly delete the source code archive. All the database associated with this archive will be removed automatically. 

Note: if the source code is needed, but just want to clean up index files, then just go the index page of the source code, see below:

Tap [Tap to clear all database] will remove the database file. Tap [delete] will only remove all the index entries in the database, the database file will not be removed. The database file’s size may not shrink after remove all the entries.