Cleaning up after 1.5 -> 2.5 migration and 2.5 -> 3.3 update - Joomla! Forum - community, help and support

i've migrated several sites 1.5 2.5. i've updated 1 of sites 2.5 3.3 (which pretty awesome). there few things i'd clean up. i'm hoping can me this.

my tables prefixed "j25". can safely remove prefix tables , change configuration file reflect change (no prefix)? cause problems in future updates?

i have several old 1.5 template styles still listed in extensions-> template manager. when attempting delete these styles receive notice

"cannot delete last style of template. uninstall/delete template go to: extensions-> extension manager-> manage-> select template deleted-> click 'uninstall'"

yet when go extensions-> extension manager-> manage, templates associated styles not on list, can't uninstall them. there way remove these styles?

these issues don't affect site @ all. know that. i'd clean them same.

advice against removing prefix. not using prefix give table names starting _ instead of j25_. shouldn't give problems not intended use.

looks went wrong migrating. styles should point existing template.
manually correct deleting unusable styles in phpmyadmin.