Managing TeX Live Installations

[Heime]

I wanted to upgrade my texlive installation and texlive-scheme-full
was installed.  I still have texlive-20250308.

Can I remove texlive-20250308.  Will texlive-scheme-full take effect
and how can I use texlive-scheme-full?  How can I then run latex on 
a file?  Calling lualatex has given me 

hagbard@kup:~$ luatex
Unable to read locale data: please check the 'locale' settings of your 
environment for consistency. Exiting now.