How do i sync non existent branches on github with local repositories?

[giraffelife]

git man page: http://bit.ly/2nvGNWB

Delete repositories that no longer exist on github, but are still on the local

$ git fetch --prune
From github.com:testacct808/mygitrepo
 x [deleted]         (none)     -> origin/superduper_feature

To clean up local repositories use git branch -d or -D

$ git branch -d superduper_feature 
Deleted branch superduper_feature (was 7e480c3).