The following commands are available in the Gnus group buffer:

SPC

Switch to the summary buffer for the group on the current line (gnus-group-read-group).

l, A s

In the group buffer, list only the groups to which you subscribe and which contain unread articles (gnus-group-list-groups; this is the default listing).

L, A u

List all subscribed and unsubscribed groups, but not killed or zombie groups (gnus-group-list-all-groups).

A k

List killed groups (gnus-group-list-killed).

A z

List zombie groups (gnus-group-list-zombies).

u

Toggle the subscription status of the group (gnus-group-toggle-subscription-at-point) on the current line. Invoking this on a killed or zombie group turns it into an unsubscribed group.

C-k

Kill the group on the current line (gnus-group-kill-group). Killed groups are not recorded in the .newsrc file, and they are not shown in the l or L listings.

DEL

Move point to the previous group containing unread articles (gnus-group-prev-unread-group).

n

Move point to the next unread group (gnus-group-next-unread-group).

p

Move point to the previous unread group (gnus-group-prev-unread-group).

q

Update your Gnus settings, and quit Gnus (gnus-group-exit).