Fetching, pulling, pushing and pruning.

See man git-fetch, section “PRUNING”.

$ git branch -r
  origin/HEAD -> origin/master
  origin/WIP-syscall
  origin/master
  origin/proc-cmdline
$ git fetch --prune
From https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux
 - [deleted]                   (none)     -> origin/WIP-syscall
 - [deleted]                   (none)     -> origin/proc-cmdline
$ git branch -r
  origin/HEAD -> origin/master
  origin/master
$