An empty sqlite database takes 74 Mb?

Why?

Because it needs to be shrunk.

Unless SQLite is running in "auto_vacuum=FULL" mode, when a large amount of data is deleted from the database file it leaves behind empty space, or "free" database pages. This means the database file might be larger than strictly necessary. Running VACUUM to rebuild the database reclaims this space and reduces the size of the database file.

Deleting tables from Database does not decrease its size in Sqlite. Its size will remain same as the maximum size attained yet