Hi,
I no longer use Wordpress either, so consider the below as a general rule, for applications which use MySQL/MariaDB as their default backend.
BEFORE YOU DO ANYTHING, backup your database and at least your config files (all files if you can too)!
I'LL ALSO RECOMMEND to test the backups; by creating a second database, and importing the database export, then modifying the config files and testing the results. After all - even a good backup has very little value if you're unable to use it!
Essentially, you just want to remove everything and start again....... your options are usually 1 of 2:
1) Because you may have added/created files, and those can cause unexpected problems in the future, the best options is likely to be removing everything and going through the installation process all over again (consider using a different installation and data directory, and a different database - which means you wont need to delete any of you old files) - and result in 2 separate environments, both running at the same time.
2) If you can't do that, then you will need to remove your data files and your config files, before going through the initial setup process again (while you may be able to reuse the same database name, I'd suggest using a different one - or deleting it first). Most systems, will/should create a new database and all the necessary tables along with any initial data. This would give you a (single) fresh/new environment.
Installing manually is often discouraged by systems like Wordpress, because they perform validation during automated setup process, and that includes server details which Wordpress certainly requires. Therefore, while you may find the SQL on Github (or where ever) you may find it difficult to manually setup the data required).
Hope this helps....
