PLEX not working - how completely delete incl. database

I installed the HACS add-on PLEX Media Server vers 3.2.4
After Service was running I was able to configure PLEX via its GUI going to IP-of-HA:32400
After adding some folders and PLEX starting to set up its Mediathek the amount of RAM used was dramaticaly increasing and later system backups as well. I assumed that this was the PLEX-database.
The media files are not stored at the HA file system but at my NAS.
Suddenly the whole system freezed, I had to make a cold start.
Now the add.on PLEX will not start any more. Error message is:

[12:19:35] INFO: Starting the Plex Media Server…
Plex Media Server is already running. Will not start…
s6-rc: info: service legacy-services successfully started
[12:19:35] INFO: Service Plex Media Server exited with code 1 (by signal 0)

I would like to completely delete this PLEX integration and delete the obsolete 11gb of PLEX database as well.
How can I do that? RAM use before the installation was 9% and today is 21%

EDIT: I was able to restart the PLEX server by using a new claim-code from PLEX.
Anyways, is it normal that so much momory are used?
My main goal was to get a media-player integration on my dashboard to play media files (music) on the frontend - but NOT on any attached smart speaker. This does not make any sense. My tablet has a display, speaker and WLAN, so why not straming right here on the dashboard???