Assuming that the automatic customization at the global level was done when AUC TeX was installed, your choice is now: will you use it? If you use it, you will benefit by having access to all the symbols and environments available for completion purposes. The drawback is slower load time when you edit a new file and perhaps too many confusing symbols when you try to do a completion.
You can disable the automatic generated global style hooks by setting
the variable TeX-auto-global to nil.
These correspond to TeX macros shared by all users of a site.
For storing automatic extracted information about the TeX macros shared by all users of a site.