Delete AWM with extension scope "global"

hey - i tried a bit in awm, created an app called ‘pattern’ and set its object variable ‘extension scope’ to ‘global’. so far, so good, as expected the app appeared in all other (sub-)wikis.
after i deleted the awm in the wiki where i created it (a sub-wiki), i still see ‘pattern’ as an available app in all other (sub-)wikis. i can hide the app via administration, but not delete it, because obviously, the app is already deleted.
my two questions:
is it correct, that the “extension scope: global” makes an awm available across all wikis, regardless of where i create it?
how do I correctly delete an awm configured in this way?

xwiki 15.10.11