Cannot re-install NextCloud du to MySQL issue

I had to uninstall Nextcloud for maintenance reason.
Willing to reinstall Nextcloud a few days later , installation script fail and I found during my investigation that this is probably due to the fact that the NextCloud database is not suppressed in MySQL when running the uninstall script.
I tried to supress this database manually and was not able to do so : error message is "#2013 - Lost connection to MySQL server during query"
I tried several change in MySQL in order to increase timeout and so but without any success
Any idea ?

Nota : I choose Nextcloud in place of ownCloud as it is in version 10 and allow the management of task within the caldav .


Some additional info here : I’m able to install / uninstall owncloud without pb.
The owncloud database can be deleted using phpMyAdmin for example
The nextcloud database still impossible to delete …